Test Session Chapter 5 States and Phases of matter (1st Year Chemistry)

Q1. Multiple Choice Questions

10 Marks

Choose the correct option for each of the following questions. Each question carries 1 mark.

1. When the vapour pressure of a liquid equals the external pressure, what phenomenon occurs?

A Sublimation

B Condensation

C Boiling

D Freezing

2. The movement of molecules in a liquid is:

A Faster than gas

B Equal to solid

C Slower than gas

D None of these

3. Which of the following factors increases surface tension?

A Increase in temperature

B Weak intermolecular forces

C Strong intermolecular forces

D Low pressure

4. The boiling point of a liquid is the temperature at which its vapour pressure equals:

A 100 torr

B 1 atm

C External pressure

D Surface tension

5. Water has a higher boiling point than alcohol because:

A Water is denser

B Alcohol is heavier

C Water has stronger intermolecular forces

D Alcohol freezes faster

6. At the boiling point, further heating is used to:

A Increase temperature

B Decrease pressure

C Break intermolecular forces

D Create surface tension

7. Liquid crystals exist in a phase that is:

A Fully liquid

B Full solid

C Between liquid and solid

D None of these

8. What makes liquid crystals suitable for LCD technology?

A Their solid structure

B Their ability to block sound

C Their optical and flow properties

D Their chemical reactivity

9. The molecules of liquid crystal:

A Move randomly in all directions

B Cannot rotate

C Have restricted rotational freedom

D Are perfectly aligned like in solids

10. Anisotropy in liquid crystals means:

A They have different colors

B They break easily

C They show different properties in different directions

D They dissolve in all solvents

Q2. Short Answer Questions

15 Marks

Write down short answers to the following questions.

Explain, at a molecular level, why evaporation leads to a cooling effect.
The viscosity of honey is higher than water, explain why. (Quick Check 5.4)
Which of the liquids in each of the following pairs has a higher vapour pressure?
(i) Alcohol, glycerine
(ii) Petrol, kerosene
(iii) Mercury, water (Quick Check 5.5)
Why food cooking is difficult in the areas with high altitudes? (Quick Check 5.6)
Mention the properties of liquid crystals in which they resemble liquids. (Quick Check 5.8)
Why can gases be compressed easily?
Why is the diffusion rate of a liquid slower than that of a gas?
What is the evidence that liquid molecules are in constant motion?
What do boiling points of halogens increase down the group?
Explain why water has a high heat of vaporization.
Why does ammonia form fewer hydrogen bonds than water?
What is the SI unit of viscosity?
What is meant by dynamic equilibrium between evaporation and condensation?
How do intermolecular forces affect vapour pressure?
Give two examples each of crystalline and amorphous solids.

Q3. Detailed Answer Questions

10 Marks

Write detailed answers to the following questions. (Answer any 2)

1. Describe the following properties of crystalline solids.
(i) Geometrical shape
(ii) Melting point
(iii) Cleavage plane
(iv) Habit of a crystal

2. Discuss the influence of hydrogen bonding on the physical properties of water, including boiling point, density, viscosity, and surface tension. Use diagrams where necessary.

[Space for diagrams illustrating hydrogen bonding in water]

3. Explain the major uses of liquid crystals in daily life.

Chemistry Examination

Chapter 5: States and Phases of Matter

MCQ Section Score