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:
- Physical Sciences – Deals with non-living systems (Physics, Chemistry).
- 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:
- Classical Mechanics – Motion of objects
- Thermodynamics – Heat and energy
- Electromagnetism – Electricity & magnetism
- Optics – Study of light
- 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:
- Biophysics – Physics applied to biological systems
- Nanotechnology – Physics + Chemistry + Engineering
- 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:
- Observation – Noticing a phenomenon
- Question – Asking “why” or “how”
- Hypothesis – Making an educated guess
- Experimentation – Testing the hypothesis
- Analysis – Examining results
- 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)
