When heat energy is removed, two changes are observed:

Change A: Gas changes phases to a liquid.

Change B: Liquid changes phases to a solid.

What are the names for phase changes A and B?

A is condensation and B is freezing.

A is condensation and B is melting.

A is evaporation and B is freezing.

A is evaporation and B is melting.

Answer: A is condensation and B is freezing.

The process in which the gas changes to the liquid phase due to the removal of heat is known as condensation. Rains are formed in this way. The water vapour rises. As it raises above it loses heat and then cools down and condenses and comes down as rainfall.

The process in which the liquid changes to a solid on removal of heat is known as freezing. Formation of ice is an example. When the heat is removed at - 4 degree Celsius the water freezes to ice.

A is condensation and B is freezing.

Explanation:

Condensation is the process in which a gas changes into a liquid. Evaporation is the process in which a liquid changes into a gas. Freezing is when liquid changes to solid/solid liquid. Melting is when a solid/solid liquid changes to liquid.

In change A, a gas changes to a liquid; this is called condensation

In change B, a liquid changes into a solid; this is called freezing.