Melting

Q.

A sample of water under study was found to boil at $102°\mathrm{C}$ at normal temperature and pressure. Is the water pure? Will this water freeze at $0°\mathrm{C}$? Comment.

Q.

Can a small volume of water in a kettle fill a kitchen with steam? Justify.

Q.

How does ice gets converted into liquid water?

1. Ice converts into liquid water by absorbing heat.

2. Ice converts into liquid water neither by absorbing nor by releasing heat.

3. Ice converts into liquid water by releasing heat.

4. It is not possible to find.

Q.

The melting point and the freezing point for all substances are always equal.

1. True
2. False

Q.

The melting point of a substance is equal to its boiling point.

1. True
2. False

Q.

What is the relationship between melting point and freezing point of a body?

1. It cannot be determined

2. Freezing point is greater than melting point

3. Both occur at the same temperature

4. Melting point is greater than freezing point

Q.

Define melting point. Give its value for water.

Q.

why are the melting and freezing point of a substance same?

Q.

Write T true and ‘F’ for false statement

. The melting point of wax is 55°C.

1. True
2. False

Q.

Melting and freezing occur at same temperature.

1. True

2. False

Q.

Sublimation is _____ [considered/not considered] a change of state of matter.

Q. When salt is added on an ice cube its melting point ______ .

1. increases
2. decreases
3. remains same
4. fluctuates

Q.

Define the following terms:

(b) Boiling

Q.

Name the point when water changes into gaseous state.

Q.

Define

Melting point

Q. It is known that wax contracts on solidification. If molten wax is taken in a large vessel and it is allowed to cool slowly, then

1. It will start solidifying from the top downward
2. It will start solidifying from the bottom upward
3. It will start solidifying from the middle, upward and downward
   at equal rates
4. The whole mass will solidify simultaneously

Q.

29. A group of students went for an excursion to Shimla in the month of November. A science teacher also accompanied them. There the temperature fell to -10⁰C. They took some ice cubes subjected them to heating while keeping a thermometer in the container. The students monitoring the reading of thermometer till the entire ice melted into water. All of them went to their science teacher and showed him their observations. He asked them to discuss among themselves and give a proper justification for the observations on the readings at the various stages.

Q.

During melting, intermolecular force will ______.

1. increase

2. decrease

3. remain same

4. None of these

Q.

When a liquid starts to boil its temperature remains constant.

1. Increases

2. Decreases

Q. for melting of ice:
temperature of ice before heating-
temperature of ice when it is heated and melting starts-
temperature of ice and water as melting continuous-

Q. In anomalous expansion of water, density of water decreases when we go from temperature:

1. 10°C to 0°C

2. 4°C to 0°C

3. 0°C to 4°C

4. 10°C to 4°C

Q.

How does ice get converted into liquid water?

1. Heat is absorbed.

2. Heat is released.

3. Temperature increases.

4. Temperature decreases.