Melting

Q.

The process of conversion of a liquid into a solid is called

1. Sublimation

2. Condensation

3. Freezing

4. Fusion

Q. Distinguish between solids, liquids and gases on the basis of their rigidity.

Q. State three characteristics of molecules of matter which determine its solid, liquid and gaseous state.

Q.

At melting point

1. kinetic energy remains constant and potential energy increases

2. kinetic energy increases and potential energy remains constant

3. both potential energy and kinetic energy increase

4. potential energy increases with a decrease in kinetic energy

Q. The intermolecular forces are strongest in:​

1. Both a and b
2. Liquids
3. Gases
4. Solids

Q.

How does ice get converted into liquid water?

1. Temperature increases.

2. Temperature decreases.

3. Heat is released.

4. Heat is absorbed.

Q. Fill in the blanks:​

In a solid, the molecules ________ but they remain at their fixed positions.​

Q.

Liquid carbon dioxide is cooled to ______ to obtain dry ice.

1. $-50°\mathrm{C}$

2. $-78°\mathrm{C}$

3. $-87°\mathrm{C}$

4. $-5°\mathrm{C}$

Q. Fill in the blanks:​

A solid is _______ rigid.​

Q. A fixed temperature at which a solid changes into a liquid is called melting point. True or false.

1. True
2. False

Q.

The latent heat of ice is ___________ latent heat of vaizationof water.

1. higher than

2. very high than

3. lower than

4. same as

Q.

Solids are generally .(rigid/soft)

Q.

In the given figure below, the appropriate terms A and B respectively are:

1. A - Solidification, B - Vaporization, C - Sublimation

2. A - Vaporization, B - Solidification, C - Sublimation

3. A - Diffusion, B - Sublimation, C - Vaporization

4. A - Sublimation, B - Solidification, C - Vaporization

Q.

…………and gases may be considered as fluids.

Q. The temperature at which a solid is converted into liquid, is called its melting point.

1. True
2. False

Q.

The conversion of liquid into the gaseous state is known as freezing.

1. True
2. False

Q. The temperature at which a solid is converted into liquid is called _____________.

Q. Melting is a process in which solid phase changes to

1. Liquid phase
2. Any phase
3. Gaseous phase
4. Liquid phase at constant temperature

Q.

44. Why does a liquid flow easily?

Q. What happens when the temperature of a substance is increased?

1. Kinetic energy of the molecules of the substance increases.
2. Kinetic energy of the molecules of the substance decreases.
3. It does not cause any change.
4. The amplitude of vibrations of molecules of the substance about their mean position decreases.

Q.

$Solid\stackrel{?}{\to }\mathrm{Gas}$

Q. What happens when the temperature of a substance is increased?

1. Kinetic energy of the molecules of the substance increases.
2. It does not cause any change.
3. The amplitude of vibrations of molecules of the substance about their mean position decreases.
4. Kinetic energy of the molecules of the substance decreases.

Q.

Write a short note on the characteristics of solids, liquids and gases.