Chapter 8: Web Development with HTML, CSS, and JavaScript – Solved Exercise

Solved Multiple Choice Questions with Explanations & Tips

1. Which of the following tag is not a correct HTML tag?

  • (a) <div>
  • (b) <span>
  • (c) <head>
  • (d) <footer>
    Answer: None of these (All are correct HTML tags)

🔹 Explanation:
All four options (<div>, <span>, <head>, <footer>) are valid HTML tags. <div> and <span> are used for structuring and styling, <head> contains metadata, and <footer> represents the footer section of a webpage.

💡 Tip: Always check the latest HTML specifications for valid tags. You can refer to MDN Web Docs for updated information.


2. What does CSS stand for?

  • (a) Cascading Style Sheets
  • (b) Computer Style Sheets
  • (c) Creative Style Sheets
  • (d) Colorful Style Sheets
    Answer: (a) Cascading Style Sheets

🔹 Explanation:
CSS stands for Cascading Style Sheets, which is used to define the presentation of HTML documents, including layout, colors, and fonts.

💡 Tip: The word “Cascading” refers to how styles are applied in a hierarchy, from external stylesheets to inline styles.


3. Which of the following tag is used to create a hyperlink in HTML?

  • (a) <link>
  • (b) <a>
  • (c) <href>
  • (d) <nav>
    Answer: (b) <a>

🔹 Explanation:
The <a> (anchor) tag is used to create hyperlinks in HTML. The href attribute inside the <a> tag specifies the link’s destination.

💡 Tip: Use the target="_blank" attribute to open links in a new tab, like this: <a href="https://example.com" target="_blank">Click Here</a>.


4. Which property is used to change the background color in CSS?

  • (a) color
  • (b) background-color
  • (c) bgcolor
  • (d) background
    Answer: (b) background-color

🔹 Explanation:
The background-color property is used to set the background color of an element in CSS.

💡 Tip: Use color for text color and background-color for background color. Example:

body {
  background-color: lightblue;
}

5. Which HTML attribute is used to define inline styles?

  • (a) class
  • (b) style
  • (c) font
  • (d) styles
    Answer: (b) style

🔹 Explanation:
The style attribute allows inline CSS styling directly in an HTML tag.

💡 Tip: Avoid excessive use of inline styles; instead, use external CSS for better maintainability.
Example:

<p style="color: red;">This is a red text.</p>

6. Which of the following is the correct syntax for a CSS rule?

  • (a) selector {property: value;}
  • (b) selector: {property=value;}
  • (c) selector {property=value}
  • (d) selector: {property: value;}
    Answer: (a) selector {property: value;}

🔹 Explanation:
CSS rules follow the syntax:

selector {
  property: value;
}

💡 Tip: Always end CSS statements with a semicolon (;) to avoid errors.


7. In JavaScript, which markup is used for comments?

  • (a) /* */
  • (b) //
  • (c) <–
  • (d) /* */
    Answer: Both (a) and (b)

🔹 Explanation:

  • Single-line comments: // This is a comment
  • Multi-line comments: /* This is a multi-line comment */

💡 Tip: Use comments to explain code but avoid excessive commenting in obvious cases.


8. How do you include JavaScript in an HTML document?

  • (a) <script src="script.js"></script>
  • (b) <java src="script.js"></java>
  • (c) <js src="script.js"></js>
  • (d) <code src="script.js"></code>
    Answer: (a) <script src="script.js"></script>

🔹 Explanation:
JavaScript is included in HTML using the <script> tag, either inline or by linking an external file.

💡 Tip: Place <script> before the closing </body> tag to improve page load speed.


9. Which HTML tag is used to create an unordered list?

  • (a) <ol>
  • (b) <ul>
  • (c) <li>
  • (d) <list>
    Answer: (b) <ul>

🔹 Explanation:
The <ul> tag is used for unordered (bulleted) lists, whereas <ol> is for ordered (numbered) lists.

💡 Tip: Use <li> inside <ul> or <ol> to define list items.
Example:

<ul>
  <li>Item 1</li>
  <li>Item 2</li>
</ul>

10. Which tag is used to display a horizontal line in HTML?

  • (a) <br>
  • (b) <hr>
  • (c) <line>
  • (d) <hline>
    Answer: (b) <hr>

🔹 Explanation:
The <hr> (horizontal rule) tag creates a horizontal line in HTML, typically used to separate content.

💡 Tip: Customize the appearance using CSS, e.g.:

hr {
  border: 2px solid black;
}

Solved Short Questions (Simple & Easy Language)

1. What is the purpose of the <head> tag in HTML?

The <head> tag contains important information about the web page that is not visible to users. It includes:

  • The title of the page (<title>)
  • Links to CSS files (<link>)
  • Meta information (<meta>)
  • JavaScript files (<script>)

2. Explain the difference between an ordered list and an unordered list in HTML.

  • Ordered List (<ol>): It shows items in a numbered format (1, 2, 3…).
  • Unordered List (<ul>): It shows items with bullet points (●, ■, ○).

Example:

<ol>
  <li>First Item</li>
  <li>Second Item</li>
</ol>

<ul>
  <li>First Item</li>
  <li>Second Item</li>
</ul>

3. How do you add a comment in CSS?

In CSS, we use /* */ for comments.
Example:

/* This is a comment */
p {
  color: blue; /* This line changes text color to blue */
}

Comments are ignored by the browser and are used to explain code.


4. What are the different ways to apply CSS to an HTML document?

There are three ways to apply CSS:

  1. Inline CSS – Written inside the HTML tag using the style attribute. <p style="color: red;">Hello</p>
  2. Internal CSS – Written inside the <style> tag in the <head> section. <style> p { color: blue; } </style>
  3. External CSS – Written in a separate .css file and linked using <link>. <link rel="stylesheet" href="style.css">

5. How can you include JavaScript in an HTML file?

We can include JavaScript in two ways:

  1. Inline JavaScript: Inside the <script> tag in the HTML file. <script> alert("Hello World!"); </script>
  2. External JavaScript: Linking a separate JavaScript file (.js). <script src="script.js"></script>

6. Describe the syntax for creating a hyperlink in HTML.

A hyperlink is created using the <a> tag with the href attribute.
Example:

<a href="https://www.google.com">Visit Google</a>

This will create a clickable link that opens Google.


7. What is the function of the <div> tag in HTML?

The <div> tag is used to group other HTML elements together. It helps in styling and layout design.

Example:

<div style="background-color: lightgray; padding: 10px;">
  <p>This is inside a div.</p>
</div>

It is like a container for other elements.


8. How do you link an external CSS file to an HTML document?

We use the <link> tag inside the <head> section.

Example:

<link rel="stylesheet" href="style.css">

This connects an external style.css file to the HTML page.


9. What is the use of the <table> tag in HTML?

The <table> tag is used to create tables to display data in rows and columns.

Example:

<table border="1">
  <tr>
    <th>Name</th>
    <th>Age</th>
  </tr>
  <tr>
    <td>Ali</td>
    <td>15</td>
  </tr>
</table>

This will create a simple table with a border.


10. Explain the box model in CSS.

The CSS box model explains how elements are displayed on a webpage. It includes:

  1. Content – The main text or image inside the box.
  2. Padding – Space inside the box, around the content.
  3. Border – The outer edge of the box.
  4. Margin – Space outside the box, separating it from other elements.

Example:

div {
  width: 200px;
  padding: 10px;
  border: 5px solid black;
  margin: 20px;
}

This defines a box with content, padding, border, and margin.


💡 Tip for Students: Keep practicing with small HTML and CSS examples to understand better. 🚀

Solved Long Questions (Simple & Easy for Class 9)


1. Discuss the fundamental differences between HTML, CSS, and JavaScript in the context of web development.

In web development, HTML, CSS, and JavaScript work together to create a complete website. Here’s how they differ:

FeatureHTMLCSSJavaScript
PurposeStructure of a webpageStyling and designMakes the webpage interactive
What it doesDefines headings, paragraphs, images, tables, etc.Changes colors, fonts, layout, and animationsAdds buttons, forms, and real-time interactions
Example<h1>Heading</h1>h1 { color: red; }document.write("Hello!");

🔹 Simple Example:

<!DOCTYPE html>
<html>
<head>
    <style>
        h1 { color: blue; }
    </style>
    <script>
        function showMessage() {
            alert("Hello, this is JavaScript!");
        }
    </script>
</head>
<body>
    <h1>Welcome to Web Development</h1>
    <button onclick="showMessage()">Click Me</button>
</body>
</html>

HTML creates the heading and button.
CSS makes the heading blue.
JavaScript makes the button show an alert when clicked.


2. Explain the process of setting up a development environment for web development.

To start web development, you need some basic software and tools:

1. Text Editor (for writing code)

  • Notepad++ (Simple and easy)
  • VS Code (Popular among developers)

2. Web Browser (for testing webpages)

  • Google Chrome (Best for development)
  • Mozilla Firefox

3. Local Web Server (for testing advanced web pages)

  • XAMPP (For PHP and databases)

4. Steps to Set Up

  1. Install VS Code and a web browser.
  2. Open VS Code and create an index.html file.
  3. Write a basic HTML page and save it.
  4. Open the file in a web browser to see your webpage.

💡 Tip: Always save your file with .html extension before testing.


3. Create a basic HTML page that includes a header, a paragraph, an image, and a hyperlink.

Code for a simple webpage:

<!DOCTYPE html>
<html>
<head>
    <title>My First Webpage</title>
</head>
<body>
    <h1>Welcome to My Website</h1>
    <p>This is my first webpage. I am learning HTML!</p>
    <img src="image.jpg" alt="A beautiful scenery" width="300">
    <br>
    <a href="https://www.google.com">Click here to visit Google</a>
</body>
</html>

💡 Save this as index.html and open it in a browser.


4. How do you style a table using CSS? Create a sample table and apply styles to it.

HTML Table with CSS Styling

<!DOCTYPE html>
<html>
<head>
    <style>
        table {
            width: 50%;
            border-collapse: collapse;
        }
        th, td {
            border: 1px solid black;
            padding: 10px;
            text-align: center;
        }
        th {
            background-color: lightblue;
        }
        tr:nth-child(even) {
            background-color: lightgray;
        }
    </style>
</head>
<body>
    <h2>Student Marks</h2>
    <table>
        <tr>
            <th>Name</th>
            <th>Marks</th>
        </tr>
        <tr>
            <td>Ali</td>
            <td>85</td>
        </tr>
        <tr>
            <td>Sara</td>
            <td>90</td>
        </tr>
    </table>
</body>
</html>

💡 Tip: Use border-collapse: collapse; to remove space between table borders.


5. Describe the different CSS selectors and provide examples of each.

Selector TypeExampleDescription
Element Selectorp { color: red; }Styles all <p> tags.
Class Selector.highlight { color: blue; }Styles elements with class="highlight".
ID Selector#title { font-size: 20px; }Styles an element with id="title".
Group Selectorh1, h2 { text-align: center; }Styles multiple elements together.

Example:

#main {
    color: green;
}
.highlight {
    background-color: yellow;
}

💡 Tip: Use classes when styling multiple elements and IDs for unique elements.


6. Explain the process of creating a responsive web page using CSS.

A responsive webpage adjusts its layout for different screen sizes.

Example using Media Queries:

body {
    font-size: 16px;
}
@media (max-width: 600px) {
    body {
        font-size: 12px;
    }
}

🔹 Explanation:

  • The font size is 16px by default.
  • When the screen width is 600px or smaller, the font size reduces to 12px.

💡 Tip: Use flexbox and grid for better responsive design.


7. Write a JavaScript function that changes the background color of a web page when a button is clicked.

HTML + JavaScript Code:

<!DOCTYPE html>
<html>
<head>
    <script>
        function changeColor() {
            document.body.style.backgroundColor = "lightblue";
        }
    </script>
</head>
<body>
    <button onclick="changeColor()">Click to Change Color</button>
</body>
</html>

🔹 Explanation:

  • The onclick event runs the changeColor() function when the button is clicked.
  • document.body.style.backgroundColor = "lightblue"; changes the background color.

💡 Tip: You can use "random" colors using Math.random().


8. How do you add animations and transitions using CSS?

Example of a simple animation:

@keyframes move {
    from { left: 0px; }
    to { left: 200px; }
}

.box {
    position: relative;
    width: 100px;
    height: 100px;
    background-color: red;
    animation: move 2s linear infinite;
}

Example of a button with transition:

button {
    background-color: blue;
    color: white;
    padding: 10px;
    transition: background-color 0.5s;
}
button:hover {
    background-color: green;
}

🔹 Explanation:

  • Animation moves a box from left to right.
  • Transition smoothly changes button color when hovered.

💡 Tip: Use ease-in-out for smoother effects.


🔥 Conclusion: Learning HTML, CSS, and JavaScript step by step helps in building amazing websites. Keep practicing and experimenting with code! 🚀

Chapter 5 Software System – 9th Class Computer Science | Solved Exercise

Multiple Choice Questions (MCQs) with Answers, Explanations, and Tips


1. What is the primary function of an operating system?

Statement: The operating system is the core software that manages the computer’s hardware and provides an interface for users.
Options:
a) To create documents
b) To manage hardware resources and provide a user interface
c) To perform calculations
d) To design graphics
Answer: b) To manage hardware resources and provide a user interface
Explanation: The Operating System (OS) controls hardware resources, provides a user interface, and manages applications. Examples include Windows, macOS, and Linux.
Tip: Remember, an OS acts as a bridge between the hardware and the user.


2. Which software is used to enhance system performance and security?

Statement: Some specialized software helps in optimizing system performance and protecting it from threats.
Options:
a) Operating system
b) Utility software
c) Application software
d) Device drivers
Answer: b) Utility software
Explanation: Utility software includes tools like antivirus programs, disk cleanup, and system optimization tools, which help in maintaining the system’s efficiency and security.
Tip: Think of utility software as a maintenance tool for your computer.


3. What role do device drivers play in a computer system?

Statement: Device drivers are essential software components that ensure communication between the OS and hardware.
Options:
a) Manage files
b) Facilitate communication between hardware devices and the operating system
c) Create presentations
d) Enhance graphics performance
Answer: b) Facilitate communication between hardware devices and the operating system
Explanation: A device driver enables the OS to recognize and communicate with hardware components like printers, keyboards, and graphics cards. Without drivers, hardware may not function correctly.
Tip: Think of a driver as a translator between hardware and software.


4. Which of the following is an example of application software?

Statement: Application software helps users perform specific tasks.
Options:
a) Microsoft Word
b) BIOS
c) Disk Cleanup
d) Device Manager
Answer: a) Microsoft Word
Explanation: Application software is designed for end-users, such as word processors, web browsers, and media players. Microsoft Word is a word-processing application used to create and edit documents.
Tip: If it helps users perform a task, it’s application software.


5. What is the main purpose of spreadsheet software?

Statement: Spreadsheet software helps users manage and analyze numerical data efficiently.
Options:
a) To edit text documents
b) To organize and analyze data
c) To create visual content
d) To enhance system security
Answer: b) To organize and analyze data
Explanation: Spreadsheet software, like Microsoft Excel and Google Sheets, is used for data management, calculations, and financial analysis.
Tip: Spreadsheets = Numbers + Calculations.


6. How does utility software differ from application software?

Statement: Utility software serves a different purpose than application software in computing.
Options:
a) Utility software manages hardware, while application software performs specific tasks for users.
b) Utility software creates documents, while application software manages hardware.
c) Utility software performs specific tasks for users, while application software manages hardware.
d) Utility software is free, while application software is paid.
Answer: a) Utility software manages hardware, while application software performs specific tasks for users.
Explanation: Utility software focuses on system maintenance, such as antivirus, file management, and disk cleanup, while application software includes tools for document editing, browsing, and media playback.
Tip: Utility = Maintenance, Application = User Tasks.


7. Which type of software would you use to design a logo?

Statement: Graphic design software is commonly used for creating digital artwork, including logos.
Options:
a) Operating system
b) Spreadsheet software
c) Graphic design software
d) Utility software
Answer: c) Graphic design software
Explanation: Graphic design software, like Adobe Photoshop, Illustrator, and CorelDRAW, is specifically designed for creating images, logos, and digital art.
Tip: If it involves image editing or design, it’s graphic design software.


8. What is the function of system software?

Statement: System software plays a crucial role in managing computer hardware and software interactions.
Options:
a) To facilitate communication between hardware and software
b) To perform specific tasks for the user
c) To create visual content
d) To organize and analyze data
Answer: a) To facilitate communication between hardware and software
Explanation: System software includes the operating system, drivers, and utility programs, ensuring the smooth functioning of hardware and applications.
Tip: System software = Foundation of a computer system.


9. Why are operating system updates important?

Statement: Regular OS updates ensure system security, performance improvements, and bug fixes.
Options:
a) They increase screen brightness
b) They add more fonts
c) They enhance security and fix bugs
d) They improve battery life
Answer: c) They enhance security and fix bugs
Explanation: OS updates patch security vulnerabilities, improve software compatibility, and fix system bugs. Ignoring updates can lead to security risks.
Tip: Always update your OS for better security and performance!


Summary of Tips & Tricks

  1. Operating System = Manages hardware & software interactions.
  2. Utility Software = System maintenance tools like antivirus & cleanup.
  3. Device Drivers = Bridge between hardware and the OS.
  4. Application Software = Programs for user tasks (e.g., Word, Excel).
  5. Spreadsheet Software = Deals with numbers & data analysis.
  6. Graphic Design Software = Used for logos, editing, and illustrations.
  7. System Software = Backbone of the computer system.
  8. OS Updates = Improve security & fix issues.

Solved Short Questions

1. Define system software and provide two examples.

Answer: System software is a type of software that manages and controls computer hardware and provides a platform for running application software.
Examples:

  1. Operating System (OS) – Windows, Linux
  2. Utility Software – Antivirus, Disk Cleanup

Key Words: System software, Operating System, Utility Software, Hardware Management


2. Explain the primary functions of an operating system.

Answer: The operating system performs the following key functions:

  1. Hardware Management – Controls CPU, memory, and devices.
  2. User Interface – Provides a way for users to interact (GUI/CLI).
  3. File Management – Organizes, saves, and retrieves files.
  4. Security Management – Protects data through authentication.

Key Words: Hardware, User Interface, File Management, Security


3. What is utility software and why is it important?

Answer: Utility software helps maintain, optimize, and secure a computer system. It is important because it enhances system performance and ensures security.
Examples:

  • Antivirus Software – Protects from viruses.
  • Disk Cleanup – Removes unnecessary files to free space.

Key Words: Maintenance, Optimization, Security, Antivirus, Disk Cleanup


4. Describe the role of device drivers in a computer system.

Answer: A device driver is software that allows the operating system to communicate with hardware devices such as printers, keyboards, and graphics cards.

  • Without drivers, hardware cannot function properly.

Key Words: Communication, Hardware, Operating System, Printer, Keyboard


5. Differentiate between system software and application software with examples.

Answer:

FeatureSystem SoftwareApplication Software
PurposeManages hardware & system functionsHelps users perform specific tasks
ExamplesOperating System, Device DriversMS Word, Adobe Photoshop
User InteractionWorks in the backgroundDirectly used by users

Key Words: System Control, User Task, OS, Application


6. What are the main functions of spreadsheet software?

Answer:

  1. Data Organization – Stores and arranges data in rows/columns.
  2. Mathematical Calculations – Performs functions like addition and averages.
  3. Data Analysis – Creates charts and graphs.
  4. Financial Planning – Used for budgeting and accounting.

Key Words: Excel, Data Analysis, Formulas, Charts


7. How can graphic design software be used in the field of education?

Answer:

  • Helps students create visual presentations.
  • Used for designing educational posters and infographics.
  • Assists in digital art and creative projects.

Examples: Adobe Photoshop, Canva

Key Words: Education, Visual Learning, Creativity, Infographics


8. What is the significance of data backups and how can they be performed?

Answer:
Significance: Protects against data loss due to system crashes, malware, or accidental deletion.
Methods:

  1. Cloud Backup – Google Drive, OneDrive.
  2. External Storage – USB, Hard Disk.
  3. Automated Backup Software – Backup utilities in OS.

Key Words: Data Protection, Cloud Storage, USB, Security


Solved Long Questions

1. Discuss the importance of system software in a computing system.

Answer:
System software is essential because it enables the hardware and software to function together efficiently. Without system software, a computer cannot operate properly.

Importance of System Software:

  1. Hardware Management: Controls CPU, memory, and peripheral devices.
  2. User Interface: Provides GUI (Graphical User Interface) or CLI (Command Line Interface) for user interaction.
  3. File Management: Organizes, retrieves, and manages storage.
  4. Security & Protection: Manages user authentication and system security.
  5. Performance Optimization: Utility software enhances system performance.

Examples:

  • Windows, macOS (Operating Systems)
  • Antivirus, Disk Cleanup (Utility Software)

Key Words: Hardware, Security, Performance, GUI, Operating System


2. Describe the roles of operating systems, utility software, and device drivers, providing examples of each.

Answer:

Software TypeFunctionExamples
Operating SystemManages hardware & software, provides UIWindows, Linux
Utility SoftwareOptimizes system performance & securityAntivirus, Disk Cleanup
Device DriversEnables communication between OS & hardwarePrinter Driver, GPU Driver

1. Operating System:

  • Controls hardware resources.
  • Provides security features like password protection.

2. Utility Software:

  • Maintains system efficiency.
  • Examples: Disk Defragmenter (organizes files), Firewall (prevents cyber threats).

3. Device Drivers:

  • Acts as a bridge between hardware and the operating system.
  • Example: A printer driver allows the OS to send print commands.

Key Words: System Software, Utility, Driver, OS, Hardware


3. Explain the differences between system software and application software.

Answer:
System software is responsible for managing system operations, whereas application software is designed for user tasks.

Differences:

FeatureSystem SoftwareApplication Software
FunctionControls system operationsPerforms specific tasks
User InteractionWorks in the backgroundDirectly used by users
ExamplesOS, Drivers, Utility SoftwareMS Word, Photoshop

Key Words: System Operations, User Task, OS, Applications


4. Describe the process of using utility software to optimize system performance and maintain security.

Answer:
Utility software improves system performance and protects it from threats.

Steps to Optimize Performance:

  1. Run Disk Cleanup – Deletes junk files.
  2. Use Disk Defragmentation – Arranges fragmented files for faster access.
  3. Check for Malware – Use antivirus software for security.
  4. Manage Startup Programs – Reduces system boot time.

Common Utility Software:

  • Antivirus Software – Prevents viruses.
  • Firewall – Protects from cyber threats.

Key Words: Optimization, Security, Antivirus, Firewall, Disk Cleanup


5. Explain how to install, update, and troubleshoot device drivers for hardware components.

Answer:

Steps to Install/Update Drivers:

  1. Manual Installation:
    • Download driver from manufacturer’s website.
    • Install using setup file.
  2. Automatic Update:
    • Use Windows Device Manager to update drivers.
  3. Troubleshooting:
    • If hardware does not work, reinstall the driver.
    • Check for error messages and update accordingly.

Key Words: Drivers, Installation, Update, Troubleshoot, Device Manager


6. Discuss the main functions of commonly used application software.

Answer:

Types of Application Software:

TypePurposeExamples
Word ProcessingCreate/edit documentsMS Word, Google Docs
SpreadsheetOrganize & analyze dataMS Excel, Google Sheets
PresentationCreate slideshowsMS PowerPoint, Canva
Graphic DesignCreate visualsPhotoshop, Illustrator
  • Word Processors are used for writing documents.
  • Spreadsheets handle data calculations.
  • Presentation software is used for making slideshows.
  • Graphic design software creates digital artwork.

Key Words: Word Processing, Spreadsheet, Presentation, Graphic Design


Binary System Chapter 2 Solved Exercise (Computer New Syllabus)

MCQs with Answer and Explanation


1. What does ASCII stand for?

A. American Standard Code for Information Interchange
B. Advanced Standard Coder for Information Interchange
C. American Standard Communication for Information Interchange
D. Advanced Standard Communication for Information Interchange

Answer: A. American Standard Code for Information Interchange

Explanation: ASCII is a standard encoding system used to represent text in computers and communication systems. It assigns a unique numerical value to each character.

Tip: ASCII is mainly used for text encoding in English-based systems.


2. Which of the following numbers is a valid binary number?

A. 1101102
B. 11011
C. 110.11
D. 110A

Answer: B. 11011

Explanation: A binary number consists only of the digits 0 and 1. Options A and D contain invalid digits (2 and A), while C has a decimal point, making it a floating-point representation.

Tip: Valid binary numbers contain only 0s and 1s.


3. How many bits are used in standard ASCII encoding?

A. 7 bits
B. 8 bits
C. 16 bits
D. 32 bits

Answer: A. 7 bits

Explanation: Standard ASCII uses 7 bits, allowing for 128 different characters (2⁷ = 128). Extended ASCII uses 8 bits to store 256 characters.

Tip: Standard ASCII → 7 bits, Extended ASCII → 8 bits.


4. Which of the following is an advantage of Unicode over ASCII?

A. It uses fewer bits per character
B. It can represent characters from many different languages
C. It is backward compatible with binary
D. It is specific to the English language

Answer: B. It can represent characters from many different languages

Explanation: Unicode is designed to support multiple languages and scripts, whereas ASCII is limited to English characters. Unicode can store over 1 million characters.

Tip: Unicode is used globally for multi-language support.


5. How many bytes are used to store a typical integer?

A. 1 Byte
B. 2 Bytes
C. 4 Bytes
D. 8 Bytes

Answer: C. 4 Bytes

Explanation: In most programming languages and systems, a standard integer (int) requires 4 bytes (32 bits). However, this can vary based on the system architecture.

Tip:

  • Short int2 bytes
  • int4 bytes
  • Long int8 bytes

6. What is the primary difference between signed and unsigned integers?

A. Unsigned integers cannot be negative
B. Signed integers have a larger range
C. Signed integers are only used for positive numbers
D. Signed integers are slower to process

Answer: A. Unsigned integers cannot be negative

Explanation:

  • Signed integers store both positive and negative values.
  • Unsigned integers only store positive values (including zero).

Tip: Use unsigned integers when negative values are not needed to maximize range.


7. In the IEEE standard, how many bits are used for floating point precision?

A. 2 bits
B. 8 bits
C. 11 bits
D. 52 bits

Answer: B. 8 bits

Explanation: The IEEE 754 standard for single-precision floating-point numbers allocates 8 bits for the exponent, 23 bits for the mantissa, and 1 bit for the sign.

Tip:

  • Single precision → 32 bits (8-bit exponent)
  • Double precision → 64 bits (11-bit exponent)

8. What is the approximate range of values for single-precision floating-point numbers?

A. 1.4 × 10⁻⁴⁵ to 3.4 × 10³⁸
B. 4.9 × 10⁻³²⁴ to 1.8 × 10³⁰⁸
C. 1.4 × 10⁻¹⁰ to 1.8 × 10¹⁵
D. 0 to 1.8 × 10³⁸

Answer: A. 1.4 × 10⁻⁴⁵ to 3.4 × 10³⁸

Explanation: In IEEE 754 single-precision, the exponent range allows representation from approximately 1.4 × 10⁻⁴⁵ (smallest positive number) to 3.4 × 10³⁸ (largest number).

Tip:

  • Single precision32-bit floating point
  • Double precision64-bit floating point

9. What are the tiny dots that make up an image displayed on a screen?

A. Pixels
B. Bits
C. Bytes
D. Nodes

Answer: A. Pixels

Explanation: A pixel (short for “picture element”) is the smallest unit of a digital image. Each pixel has RGB values to define its color.

Tip: More pixels = higher image resolution.


10. In an RGB color model, what does RGB stand for?

A. Red, Green, Blue
B. Red, Gray, Black
C. Right, Green, Blue
D. Red, Green, Brown

Answer: A. Red, Green, Blue

Explanation: The RGB model is used in digital displays, where Red, Green, and Blue light combine at different intensities to create colors.

Tip: RGB is used for screens, while CMYK (Cyan, Magenta, Yellow, Black) is used for printing.


Summary of Key Takeaways:

  1. ASCII is a 7-bit character encoding system.
  2. Binary numbers contain only 0s and 1s.
  3. Unicode supports multiple languages.
  4. Standard integer size is 4 bytes.
  5. Unsigned integers cannot be negative.
  6. IEEE floating-point precision follows the IEEE 754 standard.
  7. Pixels are the smallest units of an image.
  8. RGB model is used for display screens.

Short Questions


1. What is the primary purpose of the ASCII encoding scheme?

Answer: ASCII (American Standard Code for Information Interchange) is used to represent text in computers by assigning unique numeric values to characters.

🔑 Key Words: Character encoding, text representation, numeric values, computers.


2. Explain the difference between ASCII and Unicode.

Answer: ASCII uses 7 or 8 bits to represent English characters, while Unicode supports multiple languages by using 16, 32, or more bits per character.

🔑 Key Words: ASCII, Unicode, character encoding, multi-language support, bit size.


3. How does Unicode handle characters from different languages?

Answer: Unicode assigns a unique code point to each character, enabling representation of text in multiple languages and symbols.

🔑 Key Words: Unicode, code points, multilingual, character representation.


4. What is the range of values for an unsigned 2-byte integer?

Answer: An unsigned 2-byte integer (16 bits) ranges from 0 to 65,535 (2¹⁶ – 1).

🔑 Key Words: Unsigned integer, 2-byte, 16-bit, range, binary representation.


5. Explain how a negative integer is represented in binary.

Answer: Negative integers are represented using two’s complement notation, where the most significant bit (MSB) acts as the sign bit.

🔑 Key Words: Negative integers, two’s complement, sign bit, binary representation.


6. What is the benefit of using unsigned integers?

Answer: Unsigned integers provide a larger range of positive values since they do not reserve a bit for the sign.

🔑 Key Words: Unsigned, positive values, extended range, no sign bit.


7. How does the number of bits affect the range of integer values?

Answer: More bits allow for a larger range of integers, while fewer bits limit the range and can cause overflow.

🔑 Key Words: Bits, integer range, overflow, binary representation.


8. Why are whole numbers commonly used in computing for quantities that cannot be negative?

Answer: Whole numbers (unsigned integers) are used for values that cannot be negative, such as memory addresses, pixel counts, and file sizes, to maximize range and efficiency.

🔑 Key Words: Whole numbers, unsigned, non-negative, memory addresses, efficiency.


9. How is the range of floating-point numbers calculated for single precision?

Answer: The range of IEEE 754 single-precision floating-point numbers is determined by the 8-bit exponent and 23-bit mantissa, allowing values from ±1.4 × 10⁻⁴⁵ to ±3.4 × 10³⁸.

🔑 Key Words: Floating-point, single precision, IEEE 754, exponent, mantissa.


10. Why is it important to understand the limitations of floating-point representation in scientific computing?

Answer: Floating-point representation introduces rounding errors and precision loss, which can impact accuracy in scientific and engineering calculations.

🔑 Key Words: Floating-point, precision loss, rounding errors, scientific computing, accuracy.


Long Questions


1. Explain how characters are encoded using Unicode. Provide examples of characters from different languages and their corresponding Unicode code points.

Answer:
Unicode is a system used to represent characters from almost all the languages of the world. Each character is assigned a unique code point (a unique number) that allows computers to understand and display text correctly.

Examples of Unicode Characters:

  • English Letter ‘A’ → Unicode: U+0041
  • Arabic Letter ‘ب’ (Baa) → Unicode: U+0628
  • Chinese Character ‘你’ (You) → Unicode: U+4F60
  • Hindi Letter ‘अ’ (A) → Unicode: U+0905

🔹 Why is Unicode important?

  • It allows different languages to be displayed on computers.
  • It prevents errors when sending text in different languages.

2. Describe in detail how integers are stored in computer memory.

Answer:
Computers store integers in binary format (0s and 1s). The number of bits (8-bit, 16-bit, 32-bit, etc.) determines how large a number can be stored.

🔹 Types of Integer Storage:

  1. Unsigned Integers → Can only store positive numbers (e.g., 0 to 255 in 8-bit storage).
  2. Signed Integers → Can store both positive and negative numbers using two’s complement notation.

🔹 Example:

  • A 4-bit unsigned integer can store values from 0000 (0) to 1111 (15).
  • A 4-bit signed integer (two’s complement) can store values from -8 to 7.

3. Explain the process of converting a decimal integer to its binary representation and vice versa. Include examples of both positive and negative integers.

Answer:

Converting Decimal to Binary (Positive Number):

🔹 Example: Convert 13 to binary.

  1. Divide by 2 and record the remainder:
    • 13 ÷ 2 = 6, remainder = 1
    • 6 ÷ 2 = 3, remainder = 0
    • 3 ÷ 2 = 1, remainder = 1
    • 1 ÷ 2 = 0, remainder = 1
  2. Read the remainders from bottom to top → 1101₂

🔹 Example: Convert -13 to binary using two’s complement (8-bit representation):

  1. Convert 13 to binary → 00001101
  2. Take two’s complement (invert bits and add 1):
    • Invert: 11110010
    • Add 1: 11110011
  3. So, -13 in binary = 11110011₂

🔹 Binary to Decimal Example:
Convert 1011₂ to decimal:
(1 × 2³) + (0 × 2²) + (1 × 2¹) + (1 × 2⁰) = 8 + 0 + 2 + 1 = 11


4. Perform the following binary arithmetic operations:

a) Multiplication of 101₂ by 11₂

Answer: Convert to decimal:

  • 101₂ = 5
  • 11₂ = 3
  • 5 × 3 = 15

Now multiply in binary:

     101
   ×  11
  --------
     101     (101 × 1)
+ 1010      (101 × 1, shift left)
  --------
   1111₂

Final Answer: 1111₂ (15 in decimal)


b) Division of 1100₂ by 10₂

Answer: Convert to decimal:

  • 1100₂ = 12
  • 10₂ = 2
  • 12 ÷ 2 = 6

Now divide in binary:

  1100 ÷ 10  
= 0110₂ (6 in decimal)

Final Answer: 0110₂ (6 in decimal)


5. Add the following binary numbers:

a) 101₂ + 110₂

    101
  + 110
  ------
   1011₂

Final Answer: 1011₂ (11 in decimal)

b) 1100₂ + 1011₂

    1100
  + 1011
  ------
   10111₂

Final Answer: 10111₂ (23 in decimal)


6. Convert the following numbers to 4-bit binary and add them:

a) 7 + (-4)

Convert to 4-bit binary:

  • 7 → 0111₂
  • -4 (Two’s complement) → 1100₂
    0111
  + 1100
  ------
   0011₂

Final Answer: 0011₂ (3 in decimal)


b) -5 + 3

Convert to 4-bit binary:

  • -5 (Two’s complement) → 1011₂
  • 3 → 0011₂
    1011
  + 0011
  ------
   1110₂

Final Answer: 1110₂ (-2 in decimal)


7. Solve the following binary operations:

a) 1101₂ – 0100₂

  1101
- 0100
------
  1001₂

Final Answer: 1001₂ (9 in decimal)

b) 1010₂ – 0011₂

  1010
- 0011
------
  0111₂

Final Answer: 0111₂ (7 in decimal)

c) 1000₂ – 0110₂

  1000
- 0110
------
  0010₂

Final Answer: 0010₂ (2 in decimal)

d) 1110₂ – 100₂

  1110
- 0100
------
  1010₂

Final Answer: 1010₂ (10 in decimal)


Summary:

  • Binary arithmetic follows simple addition/subtraction rules like decimal numbers.
  • Two’s complement is used for negative numbers.
  • Multiplication and division in binary work similarly to decimal operations.

9th Class Computer Chapter 1: Introduction to Systems – Solved Exercise

Get the complete solved exercise for 9th Class Computer Chapter 1 – Introduction to Systems. Detailed answers to MCQs, short and long questions with explanations.


1. What is the primary function of a system?

Statement: The primary function of a system is its main purpose or objective.
Options:
a) To work independently
b) To achieve a common goal
c) To create new systems
d) To provide entertainment
Answer: b) To achieve a common goal
Explanation: A system is designed to work as an interconnected unit with different components working together to achieve a specific goal.
Tip: Remember that a system is about coordination and achieving objectives efficiently.


2. What is one of the fundamental concepts of any system?

Statement: A fundamental concept of a system refers to a core characteristic that defines it.
Options:
a) Its size
b) Its objective
c) Its age
d) Its price
Answer: b) Its objective
Explanation: Every system has an objective that determines its purpose and functioning. Size, age, and price are variable attributes but not fundamental.
Tip: Always look for the core reason why a system exists.


3. What is an example of a simple system?

Statement: A simple system consists of few components and is easy to understand.
Options:
a) A human body regulating temperature
b) A computer network
c) The Internet
Answer: a) A human body regulating temperature
Explanation: A simple system has minimal elements and direct relationships. The human body’s temperature regulation (homeostasis) is a straightforward system, while networks and the Internet are complex systems.
Tip: Think of simplicity as minimal interaction and direct cause-effect relationships.


4. What type of environment remains unchanged unless the system provides an output?

Statement: The type of environment that does not change unless influenced by a system.
Options:
a) Dynamic
b) Static
c) Deterministic
d) Non-deterministic
Answer: b) Static
Explanation: A static environment remains constant and does not change unless the system actively alters it. Dynamic environments change regardless of system outputs.
Tip: “Static” means unchanging, while “dynamic” means continuously evolving.


5. What are the basic components of a system?

Statement: A system consists of essential elements that define its structure and function.
Options:
a) Users, hardware, software
b) Objectives, components, environment, communication
c) Inputs, outputs, processes
d) Sensors, actuators, controllers
Answer: c) Inputs, outputs, processes
Explanation: Every system has inputs (resources), processes (actions), and outputs (results), forming the essential building blocks.
Tip: If asked about components, always break a system down into inputs, processes, and outputs.


6. What concept does the theory of systems aim to understand?

Statement: The theory of systems focuses on analyzing specific aspects of a system.
Options:
a) Hardware design
b) System interactions and development over time
c) Software applications
Answer: b) System interactions and development over time
Explanation: System theory studies how different parts of a system interact and evolve over time.
Tip: Think about how elements of a system influence each other over time.


7. What role does the Operating System (OS) play in a computer?

Statement: The OS has an important function in managing system operations.
Options:
a) It only coordinates and executes instructions
b) It temporarily stores data and instructions for the CPU
c) It receives input from interface components and decides what to do with it
d) It provides long-term storage of data and software
Answer: c) It receives input from interface components and decides what to do with it
Explanation: The OS manages user inputs, system resources, and coordinates execution of programs.
Tip: The OS is like a traffic controller, managing instructions, resources, and execution.


8. Which of the following describes the Von Neumann architecture’s main characteristic?

Statement: Von Neumann architecture is a foundational computer design model.
Options:
a) Separate memory for data and instructions
b) Parallel execution of instructions
c) A single memory store for both program instructions and data
d) Multiple CPUs for different tasks
Answer: c) A single memory store for both program instructions and data
Explanation: The Von Neumann architecture uses a single memory to store both instructions and data, unlike Harvard architecture, which separates them.
Tip: Remember that Von Neumann = Single memory; Harvard = Separate memory.


9. What is a disadvantage of the Von Neumann architecture?

Statement: This architecture has limitations that affect system performance.
Options:
a) Complex design due to separate memory spaces
b) Difficult to modify programs stored in memory
c) Bottleneck due to shared memory space for instructions and data
d) Lack of flexibility in executing instructions
Answer: c) Bottleneck due to shared memory space for instructions and data
Explanation: The “Von Neumann bottleneck” occurs because data and instructions share the same memory, leading to performance limitations.
Tip: If you see “Von Neumann bottleneck” in a question, it’s always about shared memory slowing performance.


Here are the solved MCQs, Short Questions, and Long Questions with well-explained answers and key terms:


Multiple Choice Questions (MCQs)

10. Which of the following transports data inside a computer among different components?

Statement: Data transfer inside a computer is managed by a specific system component.
Options:
a) Control Unit
b) System Bus
c) Memory
d) Processor
Answer: b) System Bus
Explanation: The System Bus is responsible for transferring data between different components of the computer, such as the CPU, memory, and input/output devices.
Tip: Remember that the System Bus acts as a highway for data transfer inside a computer.


Short Questions with Answers

1. Define a system. What are its basic components?

Answer:
A system is a set of interconnected components that work together to achieve a common goal.
Basic components:

  • Input (data entry)
  • Process (operations performed on data)
  • Output (result of processing)
  • Feedback (response to improve system performance)

Key terms: system, components, input, process, output, feedback


2. Differentiate between natural and artificial systems.

Answer:

  • Natural System: Occurs naturally (e.g., the human body, the ecosystem).
  • Artificial System: Created by humans (e.g., computers, transportation systems).

Key terms: natural system, artificial system, ecosystem, human-made


3. Describe the main components of a computer system.

Answer:

  • Hardware: Physical parts (CPU, memory, storage, input/output devices).
  • Software: Programs and operating systems that control the hardware.
  • Users: People who operate the computer.
  • Data: Information processed by the system.

Key terms: hardware, software, users, data


4. List and describe the types of computing systems.

Answer:

  • Supercomputers: High-performance, used for scientific calculations.
  • Mainframes: Large-scale computing for enterprise applications.
  • Servers: Provide resources over a network.
  • Personal Computers (PCs): For individual use.
  • Embedded Systems: Special-purpose computers inside other devices.

Key terms: supercomputer, mainframe, server, PC, embedded system


5. What are the main components of the Von Neumann architecture?

Answer:

  • Memory Unit: Stores data and instructions.
  • Control Unit: Directs the operation of the processor.
  • Arithmetic Logic Unit (ALU): Performs calculations and logical operations.
  • Input/Output (I/O) System: Handles data entry and output.
  • System Bus: Transfers data between components.

Key terms: memory unit, control unit, ALU, input/output, system bus


6. What is the Von Neumann architecture? List its key components.

Answer:
The Von Neumann architecture is a computer design model where instructions and data are stored in the same memory.
Key Components:

  • Memory Unit
  • Control Unit
  • ALU
  • System Bus

Key terms: Von Neumann, stored program concept, memory


7. What are the main steps in the Von Neumann architecture’s instruction cycle?

Answer:

  • Fetch: Retrieve instruction from memory.
  • Decode: Interpret the instruction.
  • Execute: Perform the operation.
  • Store: Save the result.

Key terms: fetch, decode, execute, store


8. What is the Von Neumann bottleneck?

Answer:
The Von Neumann bottleneck refers to the limitation caused by a single memory pathway for both data and instructions, slowing processing speed.

Key terms: bottleneck, single memory, processing speed


9. What is a key advantage of the Von Neumann architecture?

Answer:
A key advantage is its flexibility, allowing different programs to be executed using the same hardware without modification.

Key terms: flexibility, stored program concept


10. What are the three main requirements for a computing system to function?

Answer:

  • Processing Unit (CPU): Executes instructions.
  • Memory: Stores data and instructions.
  • Input/Output (I/O) Devices: Interact with users and other systems.

Key terms: CPU, memory, input/output


Long Questions with Detailed Answers

1. Define and describe the concept of a system. Explain the fundamental components, objectives, environment, and methods of communication within a system.

Answer:
A system is a group of interconnected components working together to achieve a goal.

  • Components: Input, process, output, feedback.
  • Objectives: Purpose of the system (e.g., computing, control).
  • Environment: External conditions affecting the system.
  • Communication: Data exchange between components (signals, networks).

Key terms: system, input, process, output, feedback, communication


2. Differentiate between natural and artificial systems.

Answer:

  • Natural Systems: Exist in nature, self-regulating (e.g., ecosystem, human body).
  • Artificial Systems: Man-made, designed for a purpose (e.g., computers, transportation).

Key terms: natural, artificial, self-regulating, man-made


3. Examine the relationship between systems and different branches of science.

Answer:

  • Science: Theories behind system operations.
  • Engineering: Practical application of system designs.
  • Computer Science: Digital systems and algorithms.
  • Mathematics: Logical models for system analysis.

Key terms: science, engineering, computer science, mathematics


4. Explore the types of computing systems such as supercomputers, embedded systems, and networks.

Answer:

  • Supercomputers: Extreme processing power for simulations.
  • Embedded Systems: Found in cars, appliances, industrial machines.
  • Networks: Connect multiple computing systems for communication.

Key terms: supercomputers, embedded systems, networks


5. Describe the main characteristics of a computer system, including objectives, components, and interactions.

Answer:

  • Objectives: Computing, data processing, automation.
  • Components: CPU, memory, storage, input/output.
  • Interactions: Data exchange between components.

Key terms: computing, automation, CPU, memory


6. Explain the Von Neumann architecture of a computer.

Answer:
The Von Neumann architecture consists of:

  1. Memory (stores instructions & data).
  2. Control Unit (manages execution).
  3. ALU (performs arithmetic/logic).
  4. System Bus (transfers data).

Key terms: Von Neumann, memory, ALU, control unit


7. Provide a detailed explanation of how a computer interacts with its environment.

Answer:

  • User Input: Through keyboard, mouse, etc.
  • Processing: CPU executes tasks.
  • Output: Display, sound, prints results.
  • Network: Communicates with other systems.

Key terms: input, processing, output, network


8. Describe the steps of retrieving and displaying a file using a computer.

Answer:

  1. User Input: Clicks on a file.
  2. Processing: OS retrieves file from storage.
  3. Execution: File is opened using appropriate software.
  4. Output: Displayed on screen.

Key terms: file retrieval, OS, processing, display


Solved Exercise of Chapter 9 Nature of Science – 9th Class Physics

Get the complete solved exercise of Chapter 9 Nature of Science from 9th Class Physics for all Punjab Boards. Detailed solutions, explanations, and key concepts to help you excel in your studies.


9.1 Physics is a branch of:

Options:
(a) Social science
(b) Life science
(c) Physical science
(d) Biological science

Answer: (c) Physical science

Explanation:
Physics deals with matter, energy, motion, and forces, making it a branch of physical science rather than life or social sciences.

Tip:
Remember, physical sciences include physics, chemistry, and astronomy, while life sciences include biology and botany.


9.2 Which branch of science plays a vital role in technology and engineering?

Options:
(a) Biology
(b) Chemistry
(c) Geology
(d) Physics

Answer: (d) Physics

Explanation:
Physics is fundamental in technology and engineering as it deals with energy, motion, and mechanics, which are crucial for innovation.

Tip:
Think about physics-based technologies like electricity, mechanics, and thermodynamics in engineering applications.


9.3 Automobile technology is based on:

Options:
(a) Acoustics
(b) Electromagnetism
(c) Optics
(d) Thermodynamics

Answer: (d) Thermodynamics

Explanation:
Automobile engines operate on thermodynamic principles, particularly heat and work energy transformations.

Tip:
Thermodynamics is key in engines, while electromagnetism relates to electric motors and optics relates to lenses.


9.4 A user-friendly software application of smartphone use:

Options:
(a) Laser technology
(b) Information technology
(c) Medical technology
(d) Electronic technology

Answer: (b) Information technology

Explanation:
Smartphones run on software applications and networks, which are part of information technology.

Tip:
If it involves data processing, communication, or software, it’s information technology.


9.5 The working of refrigeration and air conditioning involves:

Options:
(a) Electromagnetism
(b) Mechanics
(c) Climate science
(d) Thermodynamics

Answer: (d) Thermodynamics

Explanation:
Refrigeration and air conditioning depend on heat transfer principles, making thermodynamics the key science behind them.

Tip:
Thermodynamics governs heat flow, while mechanics focuses on forces and motion.


9.6 What is the ultimate truth of a scientific method?

Options:
(a) Hypothesis
(b) Experimentation
(c) Observation
(d) Theory

Answer: (d) Theory

Explanation:
A scientific theory is a well-tested explanation for observations and experiments.

Tip:
Hypothesis → Experiment → Observation → Theory (Final scientific truth)


9.7 The statement “If I do not study for this test, then I will not get a good grade” is an example of:

Options:
(a) Theory
(b) Observation
(c) Prediction
(d) Law

Answer: (c) Prediction

Explanation:
Predictions are statements about future events based on prior knowledge.

Tip:
Prediction is an educated guess, while observation is direct evidence.


9.8 Which of the following are methods of investigation?

Options:
(a) Observation
(b) Experimentation
(c) Research
(d) All of these

Answer: (d) All of these

Explanation:
Scientific investigation involves observation, experimentation, and research to draw conclusions.

Tip:
Remember that science relies on multiple investigation methods to ensure accuracy.


9.9 A hypothesis:

Options:
(a) May or may not be testable
(b) Is supported by evidence
(c) Is a possible answer to a question
(d) All of these

Answer: (d) All of these

Explanation:
A hypothesis is a proposed explanation that can be tested and supported by evidence.

Tip:
A hypothesis is an initial step in scientific research, leading to experiments and theories.


9.10 A graph of an organized data is an example of:

Options:
(a) Collecting data
(b) Forming a hypothesis
(c) Analyzing data
(d) Prediction

Answer: (c) Analyzing data

Explanation:
Graphs help interpret data patterns, which is part of analysis.

Tip:
Collection → Hypothesis → Experiment → Analyze (Graph) → Conclusion


9.11 The colour of a door is brown. It is an example of:

Options:
(a) Observation
(b) Hypothesis
(c) Prediction
(d) Law

Answer: (a) Observation

Explanation:
Observations are direct sensory experiences, such as seeing colors or shapes.

Tip:
If it’s based on direct evidence, it’s an observation, not a prediction or hypothesis.


Here are the solved Short Answer, Constructed Response, and Comprehensive Questions with answers, tips & tricks, and key terms:


B. Short Answer Questions

9.1 State in your own words, what is science? Write its two main groups.

Answer:
Science is the systematic study of the natural world based on observations, experiments, and evidence. The two main groups are:

  1. Physical Sciences – Deals with non-living systems (Physics, Chemistry).
  2. Life Sciences – Studies living organisms (Biology, Botany).

Tips & Tricks:

  • Science = Observation + Experimentation
  • Physical vs. Life Science

Key Terms: Systematic study, evidence, natural world, observation


9.2 What is physics all about? Name some of its branches.

Answer:
Physics is the branch of science that deals with matter, energy, motion, and forces. It explains natural phenomena using mathematical and experimental techniques.

Branches of Physics:

  1. Classical Mechanics – Motion of objects
  2. Thermodynamics – Heat and energy
  3. Electromagnetism – Electricity & magnetism
  4. Optics – Study of light
  5. Quantum Physics – Subatomic particles

Tips & Tricks:

  • Physics explains how and why things move
  • Connect topics with real-life applications (electricity, heat, waves)

Key Terms: Matter, energy, motion, forces, laws of nature


9.3 What is meant by interdisciplinary fields? Give a few examples.

Answer:
Interdisciplinary fields combine concepts from multiple areas of science to solve problems.

Examples:

  1. Biophysics – Physics applied to biological systems
  2. Nanotechnology – Physics + Chemistry + Engineering
  3. Astrophysics – Physics applied to space and celestial bodies

Tips & Tricks:

  • Think of fields where two sciences meet (e.g., physics + medicine = medical physics)
  • Identify applications in modern technology

Key Terms: Combination, multiple sciences, technology, innovation


9.4 List the main steps of the scientific method.

Answer:

  1. Observation – Noticing a phenomenon
  2. Question – Asking “why” or “how”
  3. Hypothesis – Making an educated guess
  4. Experimentation – Testing the hypothesis
  5. Analysis – Examining results
  6. Conclusion – Accepting or rejecting the hypothesis

Tips & Tricks:

  • Follow OQHEAC (Observation, Question, Hypothesis, Experiment, Analysis, Conclusion)
  • Science is based on trial and error

Key Terms: Hypothesis, experiment, data analysis, conclusion


9.5 What is a hypothesis? Give an example.

Answer:
A hypothesis is a possible explanation for an observation that can be tested through experiments.

Example: “Plants grow faster with more sunlight.”

Tips & Tricks:

  • A hypothesis is always testable
  • It can be right or wrong, but must be verifiable

Key Terms: Prediction, testable, experiment, observation


9.6 Distinguish between a theory and a law of physics.

Answer:

  • Theory: An explanation of a natural phenomenon based on evidence (e.g., Theory of Relativity).
  • Law: A statement that describes natural behavior, always true (e.g., Newton’s Laws of Motion).

Tips & Tricks:

  • Theory = Explanation, Law = Description
  • Laws don’t change, theories can be modified

Key Terms: Explanation, proven, universal truth


9.7 What is the basis of laser technology?

Answer:
Laser technology is based on stimulated emission of radiation, where atoms emit photons in phase, creating a powerful beam of light.

Tips & Tricks:

  • LASER = Light Amplification by Stimulated Emission of Radiation
  • Used in medicine, communication, and industry

Key Terms: Stimulated emission, photons, coherent light


9.8 What is falsifiability concept? How is it important?

Answer:
Falsifiability means a hypothesis must be testable and capable of being proven wrong. It ensures scientific accuracy.

Importance:

  • Differentiates science from pseudoscience
  • Helps in refining scientific theories

Tips & Tricks:

  • If something can’t be tested, it’s not scientific
  • Example: “Aliens control human thoughts” → Not falsifiable

Key Terms: Testable, evidence-based, scientific validity


C. Constructed Response Questions

9.1 Is the theory of science an ultimate truth? Describe briefly.

Answer:
Scientific theories are not ultimate truths but well-supported explanations. They can be modified with new evidence.

Example: Newton’s theory was revised by Einstein’s relativity.


9.2 Do you think the existing laws of nature may need a change in the future?

Answer:
Yes, as new discoveries emerge, some laws may be refined or replaced.

Example: Classical physics evolved into quantum mechanics.


9.3 Describe jobs that need the use of scientific knowledge.

Answer:

  • Doctors (Medical Science)
  • Engineers (Physics & Math)
  • Environmental Scientists (Biology & Chemistry)

9.5 Comment on the statement: “A theory is capable of being proved right but not being proved wrong is not a scientific theory.”

Answer:
For a theory to be scientific, it must be falsifiable. If it cannot be tested, it is not scientific.

Example: Astrology is not science because it cannot be tested.


9.7 If a hypothesis is not testable, is the hypothesis wrong? Explain.

Answer:
A hypothesis that cannot be tested is not scientific, but it is not necessarily wrong.

Example: “Life exists in another galaxy” → It’s a claim, but not testable yet.


D. Comprehensive Questions

9.1 Describe the scope of physics. What are the main branches of physics?

Answer:
Physics studies the universe from tiny particles to massive galaxies.

Branches: Mechanics, Thermodynamics, Optics, Electromagnetism, Quantum Physics, Nuclear Physics.


9.2 What is meant by interdisciplinary fields of physics? Give three examples.

Answer:
Fields where physics is applied with other sciences.

Examples: Biophysics, Nanotechnology, Geophysics.


9.4 Differentiate between science, technology, and engineering with examples.

Answer:

  • Science: Knowledge of natural phenomena (e.g., Laws of Motion).
  • Technology: Application of science (e.g., Computers).
  • Engineering: Designing solutions (e.g., Bridges).

9.5 What is the scope of physics in everyday life? Give some examples.

Answer:
Physics is used in:

  • Electricity (Home appliances)
  • Communication (Mobile phones)
  • Transport (Vehicles)

Solved Exercise of Chapter 8 Magnetism – 9th Class Physics

Get the complete solved exercise of Chapter 8 Magnetism from 9th Class Physics for Punjab Board students. Detailed answers, explanations, and tips to help you understand magnetism concepts


8.1 Which one of the following is not a magnetic material?

Options:
(a) Cobalt
(b) Iron
(c) Aluminium
(d) Nickel

Answer: (c) Aluminium

Explanation:
Cobalt, iron, and nickel are ferromagnetic materials, meaning they exhibit strong magnetic properties. Aluminium, on the other hand, is paramagnetic, meaning it is weakly attracted to a magnetic field but does not retain magnetism.

Tip: Remember the three main ferromagnetic elements: Iron (Fe), Cobalt (Co), and Nickel (Ni). If a metal is not one of these, it is likely non-magnetic or weakly magnetic.


8.2 Magnetic lines of force:

Options:
(a) Are always directed in a straight line
(b) Cross one another
(c) Enter into the north pole
(d) Enter into the south pole

Answer: (d) Enter into the south pole

Explanation:
Magnetic field lines emerge from the north pole and enter the south pole of a magnet. They never cross each other and follow a curved path.

Tip: Remember the rule:

  • Magnetic field lines always travel from north to south outside the magnet and from south to north inside the magnet.

8.3 Permanent magnets cannot be made by:

Options:
(a) Soft iron
(b) Steel
(c) Neodymium
(d) Alnico

Answer: (a) Soft iron

Explanation:
Soft iron is highly magnetically permeable but loses its magnetism quickly. Permanent magnets require materials like steel, neodymium, and alnico, which retain magnetism for a long time.

Tip: Soft iron is used in temporary magnets (e.g., electromagnets), whereas materials like steel, neodymium, and alnico are used in permanent magnets.


8.4 Permanent magnets are used in:

Options:
(a) Circuit breaker
(b) Loudspeaker
(c) Electric crane
(d) Magnetic recording

Answer: (b) Loudspeaker

Explanation:
Permanent magnets are essential in loudspeakers because they interact with an electric current to create vibrations and produce sound. Circuit breakers and electric cranes usually use electromagnets, which can be turned on or off as needed.

Tip:

  • Loudspeakers, microphones, and some types of electric motors use permanent magnets.
  • Electromagnets are used in devices where control over magnetism is needed (e.g., cranes, circuit breakers).

8.5 A common method used to magnetise a material is:

Options:
(a) Stroking
(b) Hitting
(c) Heating
(d) Placing inside a solenoid having A.C current**

Answer: (a) Stroking

Explanation:
A material can be magnetized by stroking it with a permanent magnet in one direction. Hitting or heating disrupts the alignment of magnetic domains, causing demagnetization. An A.C. current in a solenoid does not magnetize a material effectively because the alternating current reverses direction constantly.

Tip: Stroking is an easy method to remember. Another effective method is placing the material inside a solenoid carrying D.C. current.


8.6 Magnetic field direction around a bar magnet:

Answer: (d)

Explanation:
The correct diagram should show magnetic field lines exiting the north pole and entering the south pole of the bar magnet. In the given options, option (d) correctly represents this field direction.

Tip:

  • Field lines always go from North to South outside the magnet.
  • Inside the magnet, they travel from South to North.

Solutions to MCQs, Short Answer Questions, and Constructed Response Questions


Multiple-Choice Questions (MCQs)

8.7 A steel rod is magnetized by the double touch stroking method. Which one would be the correct polarity of the AB magnet?

Options:
(a) 🔴🔵🔴🔵
(b) 🔵🔴🔵🔴
(c) 🔴🔵🔵🔴
(d) 🔵🔴🔴🔵

Answer: (c) 🔴🔵🔵🔴

Explanation:
In the double-stroke method, two permanent magnets are used to stroke a steel rod from the center outward. The end where the north pole moves becomes the south pole, and the end where the south pole moves becomes the north pole. Based on this principle, option (c) is correct.

Tip:

  • Double-stroke method: Stroke from the center to the ends with two magnets in opposite directions.
  • Single-stroke method: Use one magnet to stroke in one direction.

8.8 The best material to protect a device from an external magnetic field is:

Options:
(a) Wood
(b) Plastic
(c) Steel
(d) Soft iron

Answer: (d) Soft iron

Explanation:
Soft iron has high magnetic permeability, meaning it can redirect magnetic field lines around sensitive devices, providing effective shielding.

Tip:

  • Soft iron is used in electromagnetic shielding to prevent interference.
  • Plastic and wood do not block magnetic fields effectively.

**Short Answer

Short Answer Questions

8.1 What are temporary and permanent magnets?

Answer:

  • Temporary Magnets: These magnets exhibit magnetism only when influenced by an external magnetic field. Example: Electromagnets.
  • Permanent Magnets: These retain their magnetism even after the external magnetic field is removed. Example: Neodymium magnets.

Tip:

  • Temporary magnets lose their magnetism easily, while permanent magnets keep it for a long time.

Keywords: Electromagnets, neodymium, retain, lose magnetism


8.2 Define the magnetic field of a magnet.

Answer:

The magnetic field is the region around a magnet where its magnetic force can be detected. It is represented by magnetic field lines that originate from the north pole and end at the south pole.

Tip:

  • Stronger near poles, weaker away from the magnet.

Keywords: Region, force, field lines, north to south


8.3 What are magnetic lines of force?

Answer:

Magnetic lines of force are imaginary lines that represent the direction and strength of a magnetic field. They always travel from north to south outside the magnet and south to north inside the magnet.

Tip:

  • Field lines never cross each other.

Keywords: Imaginary, direction, never cross, north to south


8.4 Name some uses of permanent magnets and electromagnets.

Answer:

  • Permanent Magnets: Used in loudspeakers, electric motors, and refrigerator doors.
  • Electromagnets: Used in cranes, electric bells, and MRI machines.

Tip:

  • Electromagnets can be turned on and off, permanent magnets cannot.

Keywords: Loudspeaker, electric motor, crane, MRI


8.5 What are magnetic domains?

Answer:

Magnetic domains are small regions inside a material where atomic magnetic moments are aligned in the same direction. When all domains align, the material becomes magnetized.

Tip:

  • Magnetism depends on domain alignment.

Keywords: Regions, alignment, magnetized, atomic moments


8.6 Which type of magnetic field is formed by a current-carrying long coil?

Answer:

A solenoid produces a magnetic field similar to a bar magnet, with a north and south pole.

Tip:

  • Right-hand rule: Curl fingers in the direction of current, thumb points to the north pole.

Keywords: Solenoid, bar magnet, right-hand rule


8.7 Differentiate between paramagnetic and diamagnetic materials.

Answer:

  • Paramagnetic materials: Weakly attracted to a magnetic field (e.g., aluminum, platinum).
  • Diamagnetic materials: Weakly repelled by a magnetic field (e.g., copper, bismuth).

Tip:

  • Ferromagnetic materials (like iron) are strongly attracted.

Keywords: Weakly attracted, repelled, aluminum, copper


Constructed Response Questions

8.1 Two bar magnets are stored in a wooden box. Label the poles of the magnets and identify P and Q objects.

Answer:

The poles of the bar magnets should be labeled north and south such that opposite poles face each other. The objects P and Q could be soft iron keepers used to prevent demagnetization.

Tip:

  • Opposite poles attract, like poles repel.
  • Soft iron keepers help retain magnetism.

Keywords: North, south, soft iron, demagnetization


8.2 A steel bar has to be magnetized by placing it inside a solenoid such that end A of the bar becomes N-pole and end B becomes S-pole. Draw a circuit diagram of the solenoid showing the steel bar inside it.

Answer:

To magnetize the steel bar:

  • Use a solenoid with a direct current (D.C.) source.
  • Apply the right-hand rule (curl fingers in the direction of current, thumb points to the north pole).

Tip:

  • A.C. current will not magnetize permanently.

Keywords: Solenoid, D.C. current, right-hand rule, magnetization


8.3 Two bar magnets are lying as shown in the figure. A compass is placed in the middle of the gap. Its needle settles in the north-south direction. Label N and S poles of the magnets. Justify your answer by drawing field lines.

Answer:

The compass aligns with the external magnetic field and points from the north pole of one magnet to the south pole of the other magnet.

Tip:

  • A compass always points in the direction of the magnetic field.

Keywords: Compass, north-south, field lines, alignment


Solutions to Questions


Short Answer Questions

8.4 Electric current or motion of electrons produce a magnetic field. Is the reverse process true, that is, does the magnetic field give rise to electric current? If yes, give an example and describe it briefly.

Answer:

Yes, a changing magnetic field can induce an electric current. This is explained by Faraday’s Law of Electromagnetic Induction, which states that a varying magnetic field through a coil generates an electromotive force (EMF), producing current.

Example:

  • Electric generators: Rotating a coil inside a magnetic field induces a current.
  • Transformers: A changing current in one coil induces a voltage in another coil through a magnetic field.

Tip:

  • Current produces a magnetic field (Oersted’s Law).
  • Changing magnetic fields induce current (Faraday’s Law).

Keywords: Faraday’s Law, EMF, generators, induction, transformers


8.5 Four similar solenoids are placed in a circle as shown in the figure. The magnitude of current in all of them should be the same. Show by diagram, the direction of current in each solenoid such that when current in any one solenoid is switched OFF, the net magnetic field at the center O is directed towards that solenoid. Explain your answer.

Answer:

To ensure the net magnetic field at the center (O) is directed towards the solenoid that is switched OFF:

  • The current directions in solenoids must be arranged symmetrically to produce equal magnetic field contributions at O.
  • When one solenoid is turned OFF, the balance is disturbed, making the field at O point towards the inactive solenoid.

Tip:

  • Use the right-hand rule: Curl fingers in the direction of current, and the thumb shows the field direction.

Keywords: Solenoid, symmetry, current, right-hand rule, field direction


Comprehensive Questions

8.1 How can you identify whether an object is a magnet or a magnetic material?

Answer:

An object is a magnet if it:

  • Attracts and repels another magnet (showing both attraction and repulsion).
    An object is a magnetic material if it:
  • Only attracts a magnet but does not repel it.

Tip:

  • A magnet shows repulsion, magnetic materials do not.

Keywords: Attract, repel, magnet, magnetic material, test


8.2 Describe the strength of a magnetic field in terms of magnetic lines of force. Explain it by drawing a few diagrams for the fields as examples.

Answer:

  • The strength of a magnetic field is directly proportional to the density of magnetic field lines.
  • Stronger field: Closely packed lines (e.g., near poles of a magnet).
  • Weaker field: Widely spaced lines (e.g., far from the magnet).

Tip:

  • Dense lines = strong field, sparse lines = weak field.

Keywords: Field strength, density, magnetic lines, poles


8.3 What is a circuit breaker? Describe its working with the help of a diagram.

Answer:

A circuit breaker is a safety device that automatically stops current flow when there is an overload or short circuit.

  • It uses an electromagnet to detect excessive current.
  • When current exceeds a safe limit, the electromagnet pulls the switch, breaking the circuit.

Tip:

  • Used in homes, industries, and power plants for safety.

Keywords: Circuit breaker, safety, electromagnet, overload, short circuit


8.4 A magnet attracts only a magnet. Explain the statement.

Answer:

This statement is incorrect because:

  • A magnet attracts both magnetic materials (e.g., iron) and other magnets.
  • However, only another magnet can repel it, which confirms that an object is truly a magnet.

Tip:

  • Attraction does not confirm magnetism; repulsion does.

Keywords: Attraction, repulsion, test, magnetic material


8.5 Differentiate between paramagnetic, diamagnetic, and ferromagnetic materials with reference to the domain theory.

Answer:

PropertyParamagneticDiamagneticFerromagnetic
Behavior in fieldWeakly attractedWeakly repelledStrongly attracted
Magnetic domainsRandom, slightly alignOppose the fieldStrongly aligned
ExamplesAluminum, platinumCopper, goldIron, cobalt, nickel

Tip:

  • Ferromagnetic materials have strong, aligned domains.

Keywords: Domains, alignment, attraction, repulsion, iron, copper


8.6 Why are ferromagnetic materials suitable for making magnets?

Answer:

Ferromagnetic materials (e.g., iron, cobalt, nickel) are suitable because:

  • Their magnetic domains remain aligned after magnetization.
  • They have high permeability (easily magnetized).
  • They retain magnetism for a long time.

Tip:

  • Strong, aligned domains = strong permanent magnet.

Keywords: Ferromagnetic, domains, alignment, retain magnetism


Chapter 6: Solved Exercise of Mechanical Properties of Matter | 9th Class Physics

Explore the complete solved exercise of Chapter 6 – Mechanical Properties of Matter from 9th Class Physics. Simplified solutions with detailed explanations for students of the Federal Board and other boards.

MCQs


6.1

Statement: A wire is stretched by a weight WW. If the diameter of the wire is reduced to half of its previous value, the extension will become:
Options:
(a) One-half
(b) Double
(c) One-fourth
(d) Four times
Answer: (d) Four times

Explanation:
The extension of a wire is given by the formula:
ΔL∝1/d2
where dd is the diameter of the wire. Reducing the diameter to half means d′=d/2. Substituting, the extension becomes:
ΔL′=ΔL×1/(1/2)2=4ΔL
Thus, the extension increases fourfold.

Tip: Remember that wire extension depends inversely on the square of its diameter.


6.2

Statement: Four wires of the same material are stretched by the same load. Their dimensions are given below. Which of them will elongate most?
Options:
(a) Length 1 m, Diameter 1 mm
(b) Length 2 m, Diameter 2 mm
(c) Length 3 m, Diameter 3 mm
(d) Length 4 m, Diameter 0.5 mm
Answer: (d) Length 4 m, Diameter 0.5 mm

Explanation:
The elongation is directly proportional to the length and inversely proportional to the square of the diameter:
ΔL∝L/d2

Substitute the values for each option to find the highest elongation. Option (d) has the largest L/d2 ratio.

Tip: For such questions, focus on maximizing the L/d2 value.


6.3

Statement: Two metal plates of area 2 and 3 square meters are placed in a liquid at the same depth. The ratio of pressures on the two plates is:
Options:
(a) 1:1
(b) √2: √3
(c) 2:32:3
(d) 4:9
Answer: (a) 1:1

Explanation:
Pressure in a liquid depends only on depth and density, not on area. Since both plates are at the same depth, the pressures are equal.

Tip: Pressure P=ρgh. Area doesn’t influence pressure.


6.4

Statement: The pressure at any point in a liquid is proportional to:
Options:
(a) Density of the liquid
(b) Depth of the point below the surface of the liquid
(c) Acceleration due to gravity
(d) All of the above
Answer: (d) All of the above

Explanation:
Pressure in a liquid is given by:
P=ρgh
where ρ is density, g is gravitational acceleration, and h is depth.

Tip: Memorize the pressure formula and identify the variables.


6.5

Statement: Pressure applied to an enclosed fluid is:
Options:
(a) Increased in proportion to the surface area of the fluid
(b) Diminished and transmitted to the walls of the container
(c) Increased in proportion to the mass of the fluid and transmitted to each part of the fluid
(d) Transmitted unchanged to every portion of the fluid and walls of the container
Answer: (d) Transmitted unchanged to every portion of the fluid and walls of the container

Explanation:
This is Pascal’s law, which states that pressure in an enclosed fluid is distributed equally in all directions.

Tip: Always associate enclosed fluid systems with Pascal’s law.


6.6

Statement: The principle of a hydraulic press is based on:
Options:
(a) Hooke’s law
(b) Pascal’s law
(c) Principle of conservation of energy
(d) Principle of conservation of momentum
Answer: (b) Pascal’s law

Explanation:
A hydraulic press works by transmitting pressure equally through a fluid to generate a large force.

Tip: Hydraulic systems are practical examples of Pascal’s law.


6.7

Statement: When a spring is compressed, what form of energy does it possess?
Options:
(a) Kinetic
(b) Potential
(c) Internal
(d) Heat
Answer: (b) Potential

Explanation:
When a spring is compressed or stretched, it stores energy as elastic potential energy:
U=12kx2

Tip: Elastic energy is always potential.


6.8

Statement: What is the force exerted by the atmosphere on a rectangular block surface of length 50 cm and breadth 40 cm? The atmospheric pressure is 100 kPa.
Options:
(a) 20 kN
(b) 100 kN
(c) 200 kN
(d) 500 kN
Answer: (b) 100 kN

Explanation:
Force is given by:
F=P×A
Convert dimensions to meters: A=0.5×0.4=0.2 m2
Substitute P=100 kPa=100,000 Pa
F=100,000×0.2=20,000 N=20 kN

Tip: Always convert to SI units before solving.


C.6.1

Question:
A spring having spring constant k hangs vertically from a fixed point. A load of weight L, when hung from the spring, causes an extension x, provided the elastic limit of the spring is not exceeded.

Some identical springs, each with spring constant k, are arranged as shown below.

For each arrangement, complete the table by determining:
(i) The total extension in terms of x.
(ii) The spring constant in terms of k.


Understanding the problem:

  • The spring constant k tells how stiff the spring is. The larger the value, the harder it is to stretch.
  • When springs are combined (in series or parallel), their effective spring constant changes.
  • We are asked to find the total extension xx and the effective spring constant for each arrangement.

Arrangement 1: Single Spring

  • Total extension (x):
    Only one spring is used, so the total extension xx remains the same as given.
  • Effective spring constant (keff):
    The effective spring constant is the same as kk because there’s just one spring.
ArrangementTotal Extension (xx)Spring Constant (keff)
Single springxk

Arrangement 2: Two Springs in Series

  • Total extension (x):
    When springs are in series, the extension is shared by both. The total extension becomes: xtotal=x+x=2x
  • Effective spring constant (keff):
    The formula for springs in series is: 1keff=1k+1k=2k
  • Solve for keff keff=k/2
ArrangementTotal Extension (xx)Spring Constant (keff)
Two springs in series2xk/2

Arrangement 3: Two Springs in Parallel

  • Total extension (x):
    In parallel, the load is shared equally by both springs, so each spring stretches only half as much as a single spring. The total extension is: xtotal=x/2
  • Effective spring constant (keff}):
    The formula for springs in parallel is: keff=k+k=2k
ArrangementTotal Extension (xx)Spring Constant (keff)
Two springs in parallelx/22k

Final Answer:

ArrangementTotal Extension (x)Spring Constant (keff)
Single springxk
Two springs in series2xk/2
Two springs in parallelx/22k

Explanation for Students:

  1. Series combination: Springs share the same force, but their extensions add up, making the effective spring weaker (keff < k).
  2. Parallel combination: Springs share the load, reducing the extension. The system becomes stiffer (keff} > k).

Tips:

  • For series, use 1keff=1k/1+1k/2
  • For parallel, add spring constants directly: keff=k1+k

6.2 Why are springs made of steel instead of iron?

Springs are made of steel instead of iron because steel is more elastic and can return to its original shape after stretching or compressing.

6.3 Which of the following materials is more elastic?

(a) Iron
(b) Air or water

Answer: (a) Iron is more elastic than air or water because it can return to its original shape after force is removed.

6.4 How does water pressure one meter below the surface of a swimming pool compare to water pressure one meter below the surface of a very large and deep lake?

Water pressure increases with depth. However, at the same depth (one meter), the pressure is the same in both the swimming pool and the lake because pressure depends on depth and not the size of the water body.

6.5 What will happen to the pressure in all parts of a confined liquid if pressure is increased on one part? Give an example from daily life where this principle is applied.

According to Pascal’s Law, if pressure is applied to one part of a confined liquid, it is transmitted equally in all directions.

Example: When we press a toothpaste tube from one end, the paste comes out from the nozzle evenly.

6.6 If some air remains trapped within the top of the mercury column of the barometer, which is supposed to be a vacuum, how would it affect the height of the mercury column?

If air is trapped, it will exert pressure and reduce the height of the mercury column, giving incorrect atmospheric pressure readings.

6.7 How does the long neck of a giraffe not cause a problem when it raises its neck suddenly?

A giraffe has special blood vessels and valves in its neck that control blood flow, preventing sudden pressure changes and protecting the brain from excess or low blood pressure.

6.8 The end of the glass tube used in a simple barometer is not properly sealed, and some leak is present. What will be its effect?

If the glass tube is not properly sealed, air will enter, affecting the vacuum at the top. This will cause the mercury level to drop, leading to incorrect atmospheric pressure readings.

6.9 Comment on the statement, “Density is a property of a material, not the property of an object made of that material.”

Density is a property of a material, meaning that it remains the same regardless of the object’s size or shape. For example, the density of iron is the same whether it is a small nail or a large iron rod.

6.10 How is the load of a large structure estimated by an engineer?

Engineers estimate the load of large structures using principles of pressure, force distribution, and material strength. They calculate how much weight a structure can support without breaking or collapsing.


Comprehensive Questions and Answers

6.1 What is Hooke’s Law? Give three applications of this law.

Hooke’s Law states that the force needed to stretch or compress a spring is directly proportional to the distance it is stretched or compressed.

Applications:

  1. Used in vehicle suspension systems to absorb shocks.
  2. Used in measuring forces using spring balances.
  3. Helps in designing strong buildings and bridges.

6.2 Describe the working and applications of a simple mercury barometer.

A mercury barometer is a device used to measure atmospheric pressure. It consists of a long glass tube filled with mercury, inverted in a dish of mercury. The height of the mercury column indicates the atmospheric pressure.

Applications:

  1. Used in weather forecasting.
  2. Helps in measuring altitude.
  3. Used in scientific experiments to study pressure changes.

6.3 Describe Pascal’s Law. State its applications with examples.

Pascal’s Law states that when pressure is applied to a confined fluid, it is transmitted equally in all directions.

Applications:

  1. Hydraulic brakes – Used in vehicles for smooth braking.
  2. Hydraulic lifts – Used to lift heavy objects, such as cars in service stations.
  3. Syringes – Used in medical injections to push liquid into the body.

6.4 On what factors does the pressure of a liquid in a container depend? How is it determined?

The pressure of a liquid in a container depends on:

  1. Depth – The deeper the liquid, the higher the pressure.
  2. Density – Denser liquids exert more pressure.
  3. Gravity – Greater gravitational pull increases pressure.

Formula: Pressure=Density×Gravity×Height

6.5 Explain that atmospheric pressure exerts pressure. What are its applications? Give at least three examples.

Atmospheric pressure is the force exerted by air around us.

Applications:

  1. Helps in breathing by allowing lungs to expand and contract.
  2. Used in vacuum packing to keep food fresh by removing air.
  3. Used in suction pumps and syringes to draw liquid.

Short Answer Questions


6.1 Why do heavy animals like an elephant have a large area of the foot?

Answer:
Heavy animals like elephants have large feet to reduce the pressure exerted on the ground. Pressure is given by: P=F/A

By increasing the area A, the pressure P on the ground decreases, helping them walk without sinking into soft ground.

Key Point: Large area = Reduced pressure.


6.2 Why do animals like deer who run fast have a small area of the foot?

Answer:
Fast-running animals like deer have small feet to increase pressure on the ground. This increases the grip and prevents slipping, allowing them to run quickly and maintain balance.

Key Point: Small area = Increased grip and agility.


6.3 Why is it painful to walk barefoot on pebbles?

Answer:
When walking barefoot on pebbles, the area of contact with the pebbles is very small. According to the pressure formula (P=F/A), a small area increases the pressure, causing pain.

Key Point: Small contact area = High pressure = Pain.


6.4 State Pascal’s law. Give an application of Pascal’s law.

Answer:
Pascal’s Law: Pressure applied to an enclosed fluid is transmitted equally in all directions throughout the fluid.

Application: Hydraulic brakes in vehicles use Pascal’s law to amplify force and stop vehicles efficiently.

Key Point: Equal pressure distribution in fluids is the core idea.


6.5 State what do you mean by elasticity of a solid.

Answer:
Elasticity is the property of a solid to return to its original shape and size after the removal of an external force causing deformation.

Key Point: Elasticity = Ability to regain original shape.


6.6 What is Hooke’s law? Does an object remain elastic beyond the elastic limit? Give a reason.

Answer:
Hooke’s Law: Within the elastic limit, the deformation of an object is directly proportional to the applied force: F∝x

Elasticity beyond the elastic limit: No, an object does not remain elastic beyond the elastic limit. Beyond this point, the object is permanently deformed and cannot return to its original shape.

Key Point: Elastic limit = Maximum limit of elasticity.


6.7 Distinguish between force and pressure.

Answer:

ForcePressure
It is a push or pull acting on an object.It is the force applied per unit area.
Measured in newtons (N).Measured in pascals (Pa).
Formula: F=maFormula: P=F/A

Key Point: Force = Total impact; Pressure = Impact per unit area.


6.8 What is the relationship between liquid pressure and the depth of the liquid?

Answer:
Liquid pressure increases linearly with depth: P=ρgh

Where P is pressure, ρ is density, g is gravity, and h is depth.

Key Point: Greater depth = Greater liquid pressure.


6.9 What is the basic principle to measure the atmospheric pressure by a simple mercury barometer?

Answer:
The basic principle is the weight of the mercury column balances the atmospheric pressure. The height of the mercury column is directly proportional to the atmospheric pressure.

Key Point: Height of mercury = Atmospheric pressure.


6.10 State the basic principle used in the hydraulic brake system of automobiles.

Answer:
The hydraulic brake system is based on Pascal’s law, which states that pressure applied to an enclosed fluid is transmitted equally in all directions. This allows a small force on the brake pedal to generate a large braking force.

Key Point: Pascal’s law enables force amplification in braking systems.


Chapter 3 Dynamics – Solved Exercise for 9th Class Physics


3.1 When we kick a stone, we get hurt. This is due to:

  • Statement: When we apply force to kick a stone, it does not move easily.
  • Options:
    (a) inertia
    (b) velocity
    (c) momentum
    (d) reaction
  • Answer: (a) inertia
  • Explanation: The stone resists a change in its state of motion because of its inertia. Since the stone’s mass is large and it is at rest, we feel pain when force is applied.
  • Tip: Inertia is related to the resistance of an object to change its motion or state.

3.2 An object will continue its motion with constant acceleration until:

  • Statement: The object remains under an unbalanced force.
  • Options:
    (a) the net force on it begins to decrease
    (b) the resultant force on it is zero
    (c) the direction of motion changes
    (d) the resultant force is at a right angle to its tangential velocity
  • Answer: (b) the resultant force on it is zero
  • Explanation: According to Newton’s First Law, an object will remain in motion with a constant velocity unless acted upon by an external force. To change its acceleration, a force must act.
  • Tip: Remember Newton’s First Law and that forces cause changes in acceleration.

3.3 Which of the following is a non-contact force?

  • Statement: Non-contact forces act without direct physical contact.
  • Options:
    (a) Friction
    (b) Air resistance
    (c) Electrostatic force
    (d) Tension in the string
  • Answer: (c) Electrostatic force
  • Explanation: Electrostatic force acts over a distance due to charges, while the others require direct contact.
  • Tip: Non-contact forces include gravitational, magnetic, and electrostatic forces.

3.4 A ball with initial momentum pp hits a solid wall and bounces back with the same velocity. Its momentum after collision will be:

  • Statement: Momentum before and after collision is equal in magnitude but opposite in direction.
  • Options:
    (a) p= p
    (b) p=−p
    (c) p=2p
    (d) p=−2p
  • Answer: (b) p=−p
  • Explanation: The ball rebounds with the same speed but opposite direction, so the momentum becomes −p.
  • Tip: Use the principle of conservation of momentum for such problems.

3.5 A particle of mass mm moving with a velocity vv collides with another particle of the same mass at rest. The velocity of the first particle after the collision is:

  • Options:
    (a) v
    (b) −v
    (c) 0
    (d) −1/2v
  • Answer: (c) 0
  • Explanation: In a perfectly elastic collision where the masses are equal, the moving particle transfers all its velocity to the particle at rest.
  • Tip: For elastic collisions, remember velocity exchange occurs between identical masses.

3.6 Conservation of linear momentum is equivalent to:

  • Statement: The total momentum of a system remains constant if no external force acts.
  • Options:
    (a) Newton’s first law of motion
    (b) Newton’s second law of motion
    (c) Newton’s third law of motion
    (d) None of these
  • Answer: (b) Newton’s second law of motion
  • Explanation: Conservation of momentum follows from Newton’s Second Law when no external force acts on the system.
  • Tip: Link conservation laws to the underlying Newtonian principles.

3.7 An object with a mass of 5 kg moves at a constant velocity of 10 m/s. A constant force acts for 5 seconds on the object, and its velocity increases by 2 m/s in the positive direction. The force acting on the object is:

  • Options:
    (a) 5 N
    (b) 9 N
    (c) 12 N
    (d) 15 N
  • Answer: (a) 5 N
  • Explanation: Use F=ma, where a=Δvt=2/5=0.4 m/s2. Then F=5×0.4=2 N
  • Tip: Apply Newton’s Second Law and calculate acceleration first.

3.8 A large force acts on an object for a very short interval of time. In this case, it is easy to determine:

  • Statement: When force acts for a short duration, impulse is involved.
  • Options:
    (a) average force
    (b) time interval
    (c) product of force and time
    (d) none of these
  • Answer: (c) product of force and time
  • Explanation: The impulse is the product of force and time, and it changes momentum.
  • Tip: Think about the concept of impulse whenever force and time are mentioned together.

3.9 Lubricants are introduced between two surfaces to decrease friction. The lubricant:

  • Statement: Lubricants reduce direct contact and rolling resistance.
  • Options:
    (a) decreases temperature
    (b) acts as ball bearings
    (c) prevents direct contact of the surfaces
    (d) provides rolling friction
  • Answer: (c) prevents direct contact of the surfaces
  • Explanation: Lubricants reduce the roughness of surfaces and prevent contact, minimizing friction.
  • Tip: Know the role of lubricants in reducing friction to solve such questions.

Short Answer Questions (B)

3.1 What kind of changes in motion may be produced by a force?

  • Answer: A force can:
    • Start or stop an object.
    • Increase or decrease the speed of an object.
    • Change the direction of motion.
    • Change the shape of an object.

3.2 Give 5 examples of contact forces.

  • Answer:
    • Frictional force
    • Tension in a string
    • Normal force
    • Applied force (pushing or pulling)
    • Air resistance

3.3 An object moves with constant velocity in free space. How long will the object continue to move with this velocity?

  • Answer: The object will continue to move with the same velocity forever because no external force acts on it in free space (Newton’s First Law).

3.4 Define impulse of force.

  • Answer: Impulse is the product of force and the time duration for which the force acts.
    Impulse=F×t
    It changes the momentum of an object.

3.5 Why has Newton’s first law not been proved on the Earth?

  • Answer: On Earth, external forces like friction and air resistance always act on objects, so they don’t continue moving indefinitely, which makes it difficult to directly observe Newton’s First Law.

3.6 When sitting in a car which suddenly accelerates from rest, you are pushed back into the seat. Why?

  • Answer: Your body tends to stay at rest (due to inertia) while the car moves forward, so it feels like you are being pushed back.

3.7 The force expressed in Newton’s second law is a net force. Why is it so?

  • Answer: Newton’s second law considers all forces acting on an object. The net force is the total force after combining all forces acting in different directions.

3.8 How can you show that rolling friction is lesser than the sliding friction?

  • Answer: Rolling a heavy object (like a cylinder) requires less effort than sliding it because rolling friction is smaller than sliding friction. This is why wheels are used in vehicles.

3.9 Define terminal velocity of an object.

  • Answer: Terminal velocity is the constant speed an object reaches when the force of air resistance becomes equal to the weight of the object, and no more acceleration occurs.

3.10 An astronaut walking in space wants to return to his spaceship by firing a hand rocket. In what direction does he fire the rocket?

  • Answer: The astronaut should fire the rocket in the direction opposite to the spaceship. This creates a force pushing him back toward the spaceship (Newton’s Third Law).

Constructed Response Questions (C)

3.1 Two ice skaters weighing 60 kg and 80 kg push off against each other on a frictionless ice track. The 60 kg skater gains a velocity of 4 m/s. Explain how Newton’s third law applies.

  • Answer:
    • According to Newton’s third law, the force exerted by the 60 kg skater on the 80 kg skater is equal and opposite to the force exerted by the 80 kg skater on the 60 kg skater.
    • Since momentum is conserved:
      m1v1=m2v2
      60×4=80×v2
      v2=3 m/s
      The 80 kg skater moves in the opposite direction with a velocity of 3 m/s.

3.2 Inflatable air bags are installed in vehicles as safety equipment. In terms of momentum, what is the advantage of air bags over seatbelts?

  • Answer: Airbags increase the time over which the passenger’s momentum changes during a collision. This reduces the force acting on the body, minimizing injuries compared to seatbelts.

3.3 A horse refuses to pull a cart. The horse argues, “According to Newton’s third law, whatever force I exert on the cart, the cart will exert an equal and opposite force on me. Since the net force will be zero, therefore, I have no chance of accelerating (pulling) the cart.” What is wrong with this reasoning?

  • Answer:
    • The horse’s reasoning is wrong because the equal and opposite forces act on different objects.
    • The force the horse exerts on the ground pushes the horse forward (action-reaction pair). The cart moves because of the force exerted by the horse on the cart.

3.4 When a cricket ball hits high, a fielder tries to catch it. While holding the ball, he/she draws hands backward. Why?

  • Answer: By drawing hands backward, the fielder increases the time of impact. This reduces the force exerted by the ball on the hands, preventing injury.

3.5 When someone jumps from a small boat onto the river bank, why does the jumper often fall into the water? Explain.

  • Answer: When the jumper pushes the boat backward to jump, the boat moves in the opposite direction due to Newton’s Third Law. The jumper’s forward motion and the boat’s backward motion disturb balance, causing the jumper to fall.

3.6 Imagine that if friction vanishes suddenly from everything, then what could be the scenario of daily life activities?

  • Answer:
    • Walking would become impossible as we need friction to push the ground.
    • Vehicles would not move or stop, causing accidents.
    • Objects would keep sliding and never stay in place.
    • Machines would stop working because friction is needed for belts and gears to function.

Comprehensive Questions (D):


3.1 Explain the concept of force by practical examples.

Answer:
Force is a physical quantity that causes a change in the state of motion or shape of an object. It is a push or pull acting upon an object as a result of its interaction with another object.

Practical Examples of Force:

  1. Pushing a shopping cart: When you push a cart in a supermarket, you apply force to move it forward. The harder you push, the faster it moves.
  2. Kicking a football: When a football is kicked, the applied force changes its motion and direction.
  3. Opening a door: To open or close a door, a force is applied to overcome resistance (friction in the hinges).
  4. Stretching a rubber band: Pulling on a rubber band changes its shape due to the applied force.
  5. Gravity pulling objects downward: If you drop an object, the force of gravity pulls it toward the Earth.

3.2 Describe Newton’s laws of motion.

Answer:
Newton’s three laws of motion explain the relationship between an object and the forces acting upon it:

First Law (Law of Inertia):

  • Statement: An object remains at rest or in uniform motion in a straight line unless acted upon by an external force.
  • Example: A book on a table stays at rest until you push it. Similarly, a moving bicycle slows down due to friction if pedaling stops.

Second Law (Force and Acceleration):

  • Statement: The force acting on an object is equal to the product of its mass and acceleration.
    F=m⋅a
  • Example: A heavier object requires more force to accelerate than a lighter object. For example, pushing a truck requires more force than pushing a bicycle.

Third Law (Action and Reaction):

  • Statement: For every action, there is an equal and opposite reaction.
  • Example: When a swimmer pushes water backward, the water exerts an equal force forward, propelling the swimmer.

3.3 Define momentum and express Newton’s second law of motion in terms of change in momentum.

Answer:
Momentum: Momentum (pp) is the product of the mass of an object and its velocity. It measures the quantity of motion in an object.
p=m⋅v
Where:

  • pp = momentum,
  • mm = mass,
  • vv = velocity.

Newton’s Second Law in Terms of Momentum:

  • Newton’s second law can also be written as:
    F=Δp/Δt
    Where:
    Δp = change in momentum,
    Δt = time interval.
  • Explanation: Force is equal to the rate of change of momentum of an object.
  • Example: When a cricketer catches a fast ball and pulls his hands backward, he increases the time to change the ball’s momentum, which reduces the force exerted on his hands.

3.4 State and explain the principle of conservation of momentum.

Answer:
Principle of Conservation of Momentum:

  • Statement: The total momentum of an isolated system remains constant if no external forces act on it.
  • Mathematically,
    m1u1+m2u2=m1v1+m2v2
    where:
    m1,m2= masses of two objects,
    u1,u2 = initial velocities,
    v1,v2 = final velocities.

Explanation:

  • During a collision or interaction, the momentum lost by one object is gained by the other, keeping the total momentum constant.

Example:

  • When a gun is fired, the bullet moves forward while the gun recoils backward. The forward momentum of the bullet is equal to the backward momentum of the gun, conserving the total momentum.

3.5 Describe the motion of a block on a table taking into account the friction between the two surfaces. What is the static friction and kinetic friction?

Answer:
When a block is placed on a table and you try to push it, friction acts between the block and the surface.

Friction Types:

  1. Static Friction (fs):
    • Static friction acts when the object is at rest. It prevents the block from moving until a certain threshold force is applied.
    • Static friction is higher than kinetic friction.
    • Formula: fs≤μs⋅N, where μs = coefficient of static friction, N= normal force.
  2. Kinetic Friction (fk):
    • Kinetic friction acts when the object is sliding. It resists the motion of the block while it is in motion.
    • Formula: fk=μk⋅N, where μk= coefficient of kinetic friction, N = normal force.

Example:

  • When you try to push a heavy box, it initially resists (static friction). Once the force exceeds static friction, the box begins to move, and kinetic friction acts.

3.6 Explain the effect of friction on the motion of vehicles in the context of tire surface and braking force.

Answer:
Friction plays a crucial role in the motion of vehicles, both in terms of tire grip and braking.

1. Role of Tire Surface:

  • The grooves on the tire surface increase the friction between the tire and the road. This prevents the vehicle from slipping and allows better control while driving.
  • On wet or icy roads, friction reduces, causing tires to slip. Special tires with deeper grooves or chains are used in such conditions to increase friction.

2. Braking Force:

  • When brakes are applied, friction between the brake pads and the wheels slows the rotation of the tires, reducing the vehicle’s speed.
  • In the absence of friction, the vehicle would not stop.
  • Overuse of brakes may reduce friction due to overheating of the brake pads, which can lead to brake failure.

Importance of Friction in Safety:

  • Friction ensures grip and prevents skidding during turns or sudden stops.
  • Anti-lock Braking Systems (ABS) are designed to maintain optimal friction between the tires and the road, preventing skidding.

Chapter 10 Reproduction: Solved Exercise for 9th Class

Looking for solved exercises for Chapter 10: Reproduction? Our comprehensive solutions are specifically designed for 9th Class students based on the updated 2025 syllabus. Simplified answers to key topics like binary fission, vegetative propagation, and the life cycle of flowering plants are included to make your preparation easier and more efficient.


MCQs with Solutions

1. Which of the following organisms commonly reproduce by binary fission?

  • Options:
    a) Yeast
    b) Bacteria
    c) Rhizopus
    d) Plants
  • Answer: b) Bacteria
  • Explanation: Binary fission is a simple asexual reproduction method where a single cell divides into two identical daughter cells. This process is typical in prokaryotic organisms like bacteria.
  • Tip/Trick: Remember that binary fission is exclusive to unicellular organisms like bacteria.

2. What is the primary method of reproduction in yeast?

  • Options:
    a) Binary fission
    b) Spore formation
    c) Budding
    d) Fragmentation
  • Answer: c) Budding
  • Explanation: Yeast, a unicellular fungus, reproduces primarily by budding, where a new cell forms as an outgrowth of the parent cell.
  • Tip/Trick: Associate yeast with budding since it involves a “bud” growing on the parent cell.

3. Which of the following statements is true about spore formation in fungi?

  • Options:
    a) They produce spores during sexual reproduction.
    b) They produce two kinds of spores.
    c) Spores can only grow into new fungi in dry environments.
    d) Spores are produced to withstand harsh conditions.
  • Answer: d) Spores are produced to withstand harsh conditions.
  • Explanation: Spores in fungi are designed to survive extreme environmental conditions, including dryness, heat, or lack of nutrients.
  • Tip/Trick: Focus on “harsh conditions” when considering the purpose of fungal spores.

4. What happens in some bacteria during harsh conditions?

  • Options:
    a) Creation of a bud that detaches from the cell.
    b) Formation of thick-walled endospores.
    c) Splitting the cell into two identical daughter cells.
    d) Fusion of two bacterial cells.
  • Answer: b) Formation of thick-walled endospores.
  • Explanation: Endospores are highly resistant structures formed by bacteria to protect their genetic material during unfavorable conditions.
  • Tip/Trick: Recall that endospores = bacterial survival strategy.

5. Which of the following is an example of vegetative propagation through runners?

  • Options:
    a) Potato
    b) Strawberry
    c) Onion
    d) Ginger
  • Answer: b) Strawberry
  • Explanation: Strawberries propagate vegetatively through runners, which are horizontal stems that grow along the soil’s surface and develop new plants.
  • Tip/Trick: Think of “running strawberries” for runners.

6. Which plant propagates through tubers?

  • Options:
    a) Onion
    b) Potato
    c) Ginger
    d) Garlic
  • Answer: b) Potato
  • Explanation: Tubers are thickened underground stems, such as potatoes, that store food and enable vegetative propagation.
  • Tip/Trick: Visualize a potato’s “eyes” as propagation points.

7. The horizontal aboveground stem, which produces leaves and roots at its nodes:

  • Options:
    a) Stolon
    b) Bulb
    c) Rhizome
    d) Corm
  • Answer: a) Stolon
  • Explanation: Stolons are horizontal stems that grow above the ground and help plants like strawberries propagate.
  • Tip/Trick: Stolons are “above-ground runners.”

8. Which of these does NOT help a plant in vegetative propagation?

  • Options:
    a) Rhizome
    b) Corm
    c) Runner
    d) Flower
  • Answer: d) Flower
  • Explanation: Flowers are reproductive structures for sexual reproduction, not vegetative propagation.
  • Tip/Trick: Vegetative propagation relies on structures like stems, roots, and leaves, not flowers.

9. Which part of the flower is responsible for producing pollen?

  • Options:
    a) Stigma
    b) Anther
    c) Ovary
    d) Petal
  • Answer: b) Anther
  • Explanation: The anther is a part of the stamen in flowers and is responsible for producing and releasing pollen grains.
  • Tip/Trick: Associate “anther” with “pollen production.”

10. Which of the following is NOT a part of the carpel?

  • Options:
    a) Filament
    b) Style
    c) Stigma
    d) Ovary
  • Answer: a) Filament
  • Explanation: The carpel (or pistil) is the female reproductive part of the flower and consists of the stigma, style, and ovary. The filament is a part of the stamen, the male reproductive structure.
  • Tip/Trick: Remember the carpel components as “SOS” — Stigma, Ovary, Style.

11. Which structure forms the female gametophyte in flowering plants?

  • Options:
    a) Pollen grain
    b) Ovule
    c) Anther
    d) Sepal
  • Answer: b) Ovule
  • Explanation: The ovule in flowering plants develops into the female gametophyte, which contains the egg cell and is involved in reproduction.
  • Tip/Trick: The ovule = female gametophyte, while pollen grain = male gametophyte.

12. The male gametophyte in flowering plants is known as:

  • Options:
    a) Pollen grain
    b) Embryo sac
    c) Ovary
    d) Carpel
  • Answer: a) Pollen grain
  • Explanation: The pollen grain is the male gametophyte, carrying the male reproductive cells (sperm). It fertilizes the ovule during pollination.
  • Tip/Trick: Associate “pollen” with “male” and “grain” with small particles.

13. In the life cycle of flowering plants, which structure is triploid (3n)?

  • Options:
    a) Egg
    b) Fusion nucleus
    c) Endosperm nucleus
    d) Sperm
  • Answer: c) Endosperm nucleus
  • Explanation: The endosperm nucleus is triploid (3n) as it forms after the fusion of one sperm with two polar nuclei during double fertilization.
  • Tip/Trick: Triploid = three sets of chromosomes, found in endosperm for nutrient storage.

14. Embryo sac is formed inside:

  • Options:
    a) Filament
    b) Anther
    c) Style
    d) Ovule
  • Answer: d) Ovule
  • Explanation: The embryo sac is the female gametophyte and is located inside the ovule of flowering plants.
  • Tip/Trick: Embryo sac = female gametophyte = ovule.

15. Double fertilization involves:

  • Options:
    a) Fertilization of the egg by two male gametes.
    b) Fertilization of two eggs in the same embryo sac by two sperms.
    c) Fertilization of the egg and the fusion nucleus by two sperms.
    d) Fertilization of the egg and the tube cell by two sperms.
  • Answer: c) Fertilization of the egg and the fusion nucleus by two sperms.
  • Explanation: In double fertilization, one sperm fertilizes the egg to form a zygote (2n), while the other sperm fuses with two polar nuclei to form the endosperm nucleus (3n).
  • Tip/Trick: Think “double duty” — one sperm for the egg, the other for the polar nuclei.

Short Questions with Detailed Answers

1. Write a short note on budding in yeast.

  • Answer: Budding in yeast is a form of asexual reproduction. A small bud grows on the parent cell, enlarges, and eventually detaches to form a new yeast cell. This process ensures rapid multiplication under favorable conditions.

2. Write a short note on spore formation in fungi.

  • Answer: Spore formation in fungi is an asexual reproduction method where spores are produced inside a sporangium. These spores are resistant to harsh environmental conditions and germinate to form new fungi when conditions are favorable.

3. What are the advantages of spore formation in fungi and bacteria?

  • Answer:
    • Advantages:
      1. Allows survival in unfavorable conditions due to spore resistance.
      2. Enables rapid reproduction and dispersal over large areas.
      3. Requires minimal resources for reproduction.

4. Describe how vegetative propagation occurs through runners.

  • Answer: Runners are horizontal stems that grow above the ground. Nodes on these stems produce roots and shoots, which develop into new plants. This is commonly seen in plants like strawberries.

5. State how potatoes reproduce through tubers.

  • Answer: Potatoes reproduce vegetatively through tubers, which are swollen underground stems. “Eyes” on the tubers sprout into new shoots and roots, growing into new potato plants.

6. Describe the advantages and disadvantages of vegetative propagation.

  • Answer:
    • Advantages:
      1. Produces genetically identical offspring.
      2. Quick and efficient reproduction.
      3. No need for seeds or pollination.
    • Disadvantages:
      1. No genetic diversity, making plants susceptible to diseases.
      2. Overcrowding can occur, leading to competition for resources.

7. Name the four whorls present in a flower and their components.

  • Answer:
    1. Calyx: Made of sepals, protects the flower bud.
    2. Corolla: Made of petals, attracts pollinators.
    3. Androecium: Made of stamens, produces pollen.
    4. Gynoecium: Made of carpels, contains ovules.

8. Briefly describe the formation of the egg cell and polar nuclei within the embryo sac of a flower.

  • Answer: The embryo sac forms inside the ovule during megasporogenesis. One megaspore divides to form eight nuclei, which organize into cells, including the egg cell (near the micropylar end) and two polar nuclei (in the center of the sac).

9. Differentiate between:

  • i. Asexual and sexual reproduction:
    • Asexual: Single parent, no gametes, offspring identical.
    • Sexual: Two parents, gametes involved, offspring genetically diverse.
  • ii. Binary fission in bacteria and amoeba:
    • Bacteria: Simple splitting without a nucleus.
    • Amoeba: Nucleus divides first, followed by cytoplasm.
  • iii. Stolon and rhizome:
    • Stolon: Horizontal above-ground stem.
    • Rhizome: Horizontal underground stem.
  • iv. Bulb and corm:
    • Bulb: Modified stem with fleshy leaves (e.g., onion).
    • Corm: Solid, fleshy underground stem (e.g., taro).

C. Write answers in detail

1. Explain the process of binary fission in bacteria and describe how it leads to the formation of two daughter bacteria.
Binary fission is the process by which bacteria reproduce. In this process:

  • The bacterial cell grows and its DNA (genetic material) is copied.
  • The cell divides into two parts, with each part getting one copy of the DNA.
  • This results in two identical daughter bacteria.

2. What do you mean by vegetative propagation? Differentiate among different plant structures modified for vegetative propagation.
Vegetative propagation is a way plants reproduce without seeds. New plants grow from parts like roots, stems, or leaves of the parent plant.

  • Modified roots: Examples are sweet potato and carrot.
  • Modified stems: Examples are potato (tuber) and ginger (rhizome).
  • Modified leaves: An example is Bryophyllum, where buds grow on leaves.

3. Describe the ways by which humans can grow new plants by using the vegetative parts of the parent plants.
Humans grow new plants using methods like:

  • Cutting: A part of a plant like a stem or leaf is cut and planted to grow into a new plant. Example: rose.
  • Grafting: Two plants are joined together so they grow as one. Example: mango.
  • Layering: A branch of a plant is bent to the ground and covered with soil. It grows roots and becomes a new plant. Example: jasmine.

4. Define sporophyte and gametophyte. State their roles in the life cycle of plants.

  • Sporophyte: The part of the plant that produces spores. It is usually larger, like the main body of a plant.
  • Gametophyte: The part that produces gametes (sperm and egg cells). It is smaller and often hidden.
    These two alternate in the life cycle of plants. Spores from the sporophyte grow into gametophytes, and gametophytes create gametes that form a new sporophyte.

5. Explain the life cycle of flowering plants, focusing on the alternation between the gametophyte and sporophyte generations.
The life cycle of flowering plants has two stages:

  • Sporophyte stage: The main plant that produces flowers and seeds. It creates spores.
  • Gametophyte stage: The spores grow into tiny structures inside the flower, which produce male and female gametes.
    When the gametes fuse (fertilization), a seed forms, and the cycle starts again.

6. Describe how the female gametophyte (embryo sac) develops within the ovule of a flower.

  • Inside the ovule of a flower, a cell divides to form a structure with 8 nuclei.
  • This structure becomes the embryo sac, which is the female gametophyte.
  • The embryo sac has one egg cell, which combines with sperm during fertilization to form a seed.

Chapter 5: Tissues, Organs, and Organ Systems – Solved Exercise

MCQs with Answers, Explanations, and Tips


1. A higher level of organization exhibits emergent properties when:

Options:
a) Its parts function independently.
b) The sum of its parts is greater than the whole.
c) Its individual parts are more important than the whole.
d) Its parts interact to perform more functions.

Correct Answer: d) Its parts interact to perform more functions.

Explanation:
Emergent properties arise when individual components of a system interact to create functions or characteristics that are not present in the individual parts alone.

Tip:
Think of “emergence” as something greater than the sum of its parts, like teamwork in a system.


2. Which of the following demonstrates the levels of organization of the body, from simplest to most complex?

Options:
a) Cell → Organ → Tissue → Organelle → Organ system
b) Organelle → Cell → Tissue → Organ → Organ system
c) Tissue → Cell → Organelle → Organ → Organ system
d) Organ system → Tissue → Cell → Organelle → Organ

Correct Answer: b) Organelle → Cell → Tissue → Organ → Organ system

Explanation:
The correct order of organization in the body progresses from the smallest functional unit (organelle) to the largest (organ system).

Tip:
Memorize the hierarchy: “Organelle → Cell → Tissue → Organ → Organ System → Organism.”


3. At which level of organization does gas exchange occur between body and environment?

Options:
a) Organelle level in mitochondria
b) Cellular level in alveolar cells
c) Tissue level in epithelial tissues
d) Organ system level in the respiratory system

Correct Answer: d) Organ system level in the respiratory system

Explanation:
Gas exchange involves the respiratory system, particularly the lungs and alveoli, which function at the organ system level.

Tip:
Gas exchange is a system-wide process involving specialized organs like lungs.


4. The epithelial tissue in the stomach wall is responsible for producing:

Options:
a) Mucus
b) Pepsinogen
c) Hydrochloric acid
d) All of these

Correct Answer: d) All of these

Explanation:
The epithelial tissue of the stomach secretes mucus (protective layer), pepsinogen (enzyme precursor), and hydrochloric acid (to aid digestion).

Tip:
Remember that epithelial tissues in the stomach are multifunctional and secrete various substances critical for digestion.


5. In the wall of the stomach, which tissue also contains blood vessels and nerves?

Options:
a) Epithelial
b) Muscle
c) Inner connective
d) Outer connective

Correct Answer: c) Inner connective

Explanation:
Connective tissue in the stomach wall supports blood vessels and nerves, providing structural integrity and communication.

Tip:
Connective tissue “connects” and supports other tissues, including blood vessels and nerves.


6. In a leaf, which tissue is primarily responsible for photosynthesis?

Options:
a) Xylem
b) Phloem
c) Mesophyll
d) Epidermis

Correct Answer: c) Mesophyll

Explanation:
The mesophyll tissue contains chloroplasts, which carry out photosynthesis in plant leaves.

Tip:
Think of “meso” (middle) as the layer in the leaf where most photosynthesis occurs.


7. What is the primary function of the xylem tissue in a leaf?

Options:
a) To transport sugars to other parts
b) To transport water to parts of leaf
c) To synthesize chlorophyll
d) To control the opening and closing of stomata

Correct Answer: b) To transport water to parts of the leaf

Explanation:
Xylem is responsible for conducting water and dissolved nutrients from the roots to the leaves.

Tip:
Xylem = Water transport, while phloem = Food transport.


8. Which of these is a function of the human skeletal system?

Options:
a) Storing minerals and producing blood cells
b) Protecting internal organs
c) Filtering blood to remove waste products
d) Both a and b

Correct Answer: d) Both a and b

Explanation:
The skeletal system protects internal organs, stores minerals (like calcium), and produces blood cells in the bone marrow.

Tip:
Think of the skeletal system as a “protector” and a “reservoir” for minerals and blood production.


Question 9:

Statement: Which structures are responsible for the transport of food in plant bodies?
Options:
a) Xylem tissue
b) Palisade mesophyll
c) Phloem tissue
d) Spongy mesophyll

Answer: c) Phloem tissue

Explanation: Phloem tissue is responsible for the transport of food (in the form of sugars) produced during photosynthesis from the leaves to other parts of the plant. Xylem, on the other hand, is involved in transporting water and minerals.

Tips and Tricks:

  • Xylem transports “water.” Think of ‘X’ for “Xtra hydration.”
  • Phloem transports “food.” Think of ‘P’ for “Photosynthetic Products.”

Question 10:

Statement: In a plant, which of the following is the primary function of the flower?
Options:
a) Transporting water and minerals
b) Supporting leaf growth
c) Facilitating reproduction through pollination
d) Regulating gas exchange

Answer: c) Facilitating reproduction through pollination

Explanation: The flower’s main role is reproduction. It produces gametes, facilitates pollination, and forms seeds and fruits for the propagation of plants.

Tips and Tricks:

  • Remember: Flowers = Reproduction. They are like the “factories” of new plants.
  • Other processes like water transport, leaf support, and gas exchange are not related to flowers.

Short Questions with Answers:

  1. Enlist the levels of organization from cells to organ systems.
    Answer:
    • Cells → Tissues → Organs → Organ Systems → Organism
  2. What are the major roles of the epithelial tissue present in the stomach?
    Answer:
    • Protection: Lines the stomach to prevent damage from digestive acids.
    • Secretion: Produces mucus, enzymes, and hydrochloric acid.
    • Absorption: Assists in absorbing nutrients from food.
  3. How do the smooth muscles contribute to the stomach’s function?
    Answer:
    • Smooth muscles help in churning and mixing food with digestive enzymes and acids through peristaltic movements, aiding in digestion.
  4. What is the function of the palisade mesophyll in the leaf?
    Answer:
    • The palisade mesophyll is the primary site for photosynthesis due to the abundance of chloroplasts that capture sunlight.
  5. What is the role of the shoot system in plants?
    Answer:
    • The shoot system is responsible for supporting the plant, transporting water and nutrients, photosynthesis (leaves), and reproduction (flowers).
  6. What is homeostasis, and why is it important for organisms?
    Answer:
    • Homeostasis is the process by which organisms maintain a stable internal environment (e.g., temperature, pH, water balance). It is essential for optimal functioning of cells and survival.
  7. How does the human body maintain a stable internal temperature?
    Answer:
    • The body maintains temperature through mechanisms like sweating (to cool down), shivering (to generate heat), and blood flow regulation (vasodilation or vasoconstriction).
  8. Differentiate between the following:
    • Tissue and organ:
      Tissue: A group of similar cells performing a specific function.
      Organ: A structure made up of different tissues working together to perform a specific function.
    • Root system and shoot system:
      Root system: Underground part of the plant, absorbs water and nutrients.
      Shoot system: Above-ground part of the plant, supports photosynthesis and reproduction.
    • Epidermal and mesophyll tissue:
      Epidermal tissue: Outer protective layer of the leaf.
      Mesophyll tissue: Inner tissue responsible for photosynthesis.
    • Palisade and spongy mesophyll:
      Palisade mesophyll: Tightly packed cells for maximum light absorption during photosynthesis.
      Spongy mesophyll: Loosely packed cells for gas exchange.

Long Questions with Answers:

  1. Explain the levels of organization in multicellular organisms. How does each level contribute to the overall functioning of an organism?
    Answer:
    • Cells: Basic structural and functional units of life. E.g., nerve cells transmit signals.
    • Tissues: Groups of similar cells working together. E.g., muscle tissue contracts for movement.
    • Organs: Structures made of tissues performing specific tasks. E.g., the heart pumps blood.
    • Organ systems: Groups of organs working together. E.g., the digestive system processes food.
    • Organism: The entire living being, a sum of all systems working in harmony.
  2. What is a tissue level? Explain plant and animal tissues.
    Answer:
    • Tissue level: The organization where cells perform a common function.
    • Plant tissues:
      • Meristematic tissues: Growth tissues.
      • Permanent tissues: For transport (xylem, phloem), protection (epidermis), and storage (parenchyma).
    • Animal tissues:
      • Epithelial: Protection and secretion.
      • Muscle: Movement.
      • Connective: Support and binding.
      • Nervous: Signal transmission.
  3. Describe the tissue composition of the stomach. How does each tissue contribute to the digestive function of the stomach?
    Answer:
    • Epithelial tissue: Lines the stomach, secretes mucus, enzymes, and acids.
    • Muscle tissue: Smooth muscles churn food for digestion.
    • Connective tissue: Supports and binds stomach layers.
    • Nervous tissue: Regulates secretion and movement.
  4. Describe the tissue composition of the leaf. How does each tissue contribute to the functions of the leaf?
    Answer:
    • Epidermal tissue: Protects the leaf and controls water loss through stomata.
    • Mesophyll tissue: Palisade mesophyll for photosynthesis, spongy mesophyll for gas exchange.
    • Vascular tissue: Xylem transports water; phloem transports food.
  5. How do organ systems come together to form the human body?
    Answer:
    Organ systems are interdependent:
    • The digestive system provides nutrients.
    • The respiratory system supplies oxygen.
    • The circulatory system transports oxygen and nutrients.
    • The nervous system coordinates actions.
      Together, they maintain homeostasis and ensure survival.
  6. Explain the roles of the digestive system and the excretory system in maintaining homeostasis.
    Answer:
    • Digestive system: Breaks down food to provide nutrients and energy for cells.
    • Excretory system: Removes waste products like urea and excess water to prevent toxicity.
      Together, they regulate the internal environment, maintaining balance.
  7. Define homeostasis and explain its importance. Discuss how different organ systems work together to maintain homeostasis.
    Answer:
    • Homeostasis: The maintenance of a stable internal environment.
    • Importance: Ensures optimal conditions for cellular function.
    • Examples of systems working together:
      • Nervous and endocrine systems: Regulate temperature and glucose levels.
      • Respiratory and circulatory systems: Maintain oxygen and carbon dioxide balance.
      • Excretory and integumentary systems: Regulate water and salt balance.