Melting

Q.
Give reason why a wooden table should be called a solid.

Q.

The process of conversion of ice into a liquid is known as:

1. Evaporation

2. Melting

3. Condensation

4. Sedimentation

Q.

What is freezing and boiling point?

Q.

The boiling point of water and melting point of ice is _______ and _______ respectively.

Q.

Why do liquids flow ?

Q. When ice melts its particles:

1. come close together and lose energy
2. move very far apart and gain energy
3. gain energy and begin to move
4. lose energy and begin to move

Q. Which of the following best describes what happens to the particles of ice when it melts?

1. They gain energy and break up into atoms of hydrogen and oxygen.
2. They gain energy and gain freedom to move about.
3. They lose energy and escape into the atmosphere.
4. They lose energy and lose freedom to move about.

Q.

Why a wooden log cannot be compressed?

Q. In the process of melting, particles of solid absorb heat energy from the surroundings.

1. True
2. False.

Q. The process by which solid changes into liquid is known as _____.

1. fusion
2. diffusion
3. evaporation
4. sublimation

Q. The _______________ is the temperature at which a substance changes its state from solid to liquid.

1. boiling point
2. freezing point
3. melting point
4. condensation

Q.

Why do solids melt on heating?

Q. (b) What are the two conditions for the interconversion of states of matter?

Q.

Name the state of matter for the following substances :
Chlorine, copper, iron, bromine, sodium, mercury, lead, oxygen, sulphur.

Q. The temperature at which solid and liquid coexist in equilibrium is called ___

Q.

46. Why does a liquid take the shape of its container?

Q. Give two examples for each of the following:-

(c) Substances which are rigid and not compressible

Q.

Sublimation is a change in a substance from__________state to _______________ state.

Q.

Comment upon the following: compressibility

Q.

Liquids can flow because

1. its particles can easily slide over each other

2. its particles have strong inter--particle force

3. its particles have fixed position

4. Both a and b

Q.

We can easily move our hand in the air but to do the same through a solid block of wood, we need a karate expert.

Q. Give two examples for each of the following:-

(b) Substances which do not change their state.

Q. Which of the following statements are true about condensation and evaporation?

1. Condensation involves change of state from vapour to liquid.
2. Condensation involves change of state from liquid to vapour.
3. Evaporation involves change of state from liquid to vapour.
4. Evaporation involves change of state from vapour to liquid.

Q.

Comment upon the following: fluidity

Q.

The dissolving of a salt in water is a ___________ (reversible/ permanent ) change.

Q. A kind of matter which can sublime is

1. plastic
2. Water
   
3. iodine
4. milk

Q.

During the change of state of a substance, the temperature increases abruptly.

1. True
2. False

Q. For each of the following statements , say whether it describes a solid, a liquid, or a gas.

(a) Particles move about very quickly but do not leave the surface.

Q.

Dissolving salt in water is a reversible change

1. True
2. False

Q.

The melting point of ice is ______.