Melting

Q.

How dry ice is made?

Q.

The presence of impurities lower the freezing point of water.

1. True
2. False

Q.

30. The physical state of matter can be changed by changing the temperature and pressure.

1. True
2. False

Q.

Ice, water, and water vapour look different and display different _______ properties but they are _______ the same.

Q. The process through which a substance changes from a liquid to a solid is called ____________ .

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

Q.

Assertion: Solids are generally rigid and have a definite shape.

Reason: Solids have definite mass and volume.

Mark the correct choice.

1. If ‘A’ and ‘R’ are true and ‘R’ is the correct reason for ‘A’.

2. If ‘A’ and ‘R’ are true but ‘R’ is not the correct reason for ‘A’.

3. If ‘A’ is correct and ‘R’ is wrong.

4. If ‘A’ is wrong and ‘R’ is correct.

Q.

The boiling point of water at normal atmospheric pressure is:

1. 273K

2. 373K

3. 100K

4. 0°C

Q.

Freezing involves the conversion of :

1. solid to a liquid state.

2. liquid to a gaseous state.

3. liquid to a solid-state.

4. Solid to a gaseous state.

Q.

__________ is a physical process through which a solid is converted into a liquid.

1. freezing

2. cooling

3. heating

4. breaking

Q. When a bowl of ice-cream is exposed to sun, it will _______.

1. freeze
2. melt
3. condense
4. solidify

Q. A substance is said to be a ___ if its melting point is below room temperature and boiling point is above room temperature.

1. solid
2. liquid
3. gas
4. plasma

Q.

The process by which a liquid is separated and changed into a soft, semi-solid substance is called:

1. sublimation

2. evaporation

3. curdling

4. freezing

Q.

Explain the process of conversion of water to ice.

Q.

The changing of a liquid into gas on heating is called.

1. Melting

2. Boiling

3. Vaporisation

4. Condensation

Q. Identify the substance which will not melt to form liquid on heating.

1. Ice
2. Mothballs
3. Butter

Q.

Name two substances which sublime on heating.

Q. A substance is said to be a ________ , if its melting point is above room temperature under atmospheric pressure.

1. liquid
2. gas
3. solid
4. plasma

Q.

Chocolate only exists in solid form.

1. True

2. False

Q.

When ice changes to water it is an example of which process?

1. liquid to solid

2. gas to solid

3. solid to gas

4. solid to liquid

Q.

Ice melts at ____.

1. $0^{\circ }C$

2. ${24}^{\circ }C$

3. ${50}^{\circ }C$

4. ${100}^{\circ }C$

Q.

The melting point of ice on the Celsius and Kelvin scales, respectively is:

1. ${373}^{0}Cand273K$

2. $0^{0}Cand273K$

3. ${273}^{0}Cand373K$

4. ${100}^{0}Cand373K$

Q. Melting involves change in the state of the object.

1. True
2. False

Q.

Ice + ____ $\to$ Liquid water

1. Heat

2. Salt

3. Ice

4. Sugar

Q. The melting point of mercury is −39°C. The freezing point of alcohol is −98°C. How much more is the melting point of mercury as compared to the freezing point of alcohol?

Q. What happens when a solid is heated ?