Matter — Question 5

(a) When water is kept in a deep freezer, it gets cooled and changes into ice at 0°C.

Water $\xrightarrow[\text{freeze}]{\text{deep}}$ ice (0°C)

(b) When water is heated it changes into steam at 100°C.

Water $\xrightarrow{\text{heating}}$ steam (100°C)

Phenomenon of change of state of water — In ordinary conditions water is in liquid state. When it is kept in deep freezer, it changes into ice at 0°C. But ice changes back into liquid state when ice is kept at room temperature.

On heating water, it changes into steam at 100°C. On cooling steam changes back into liquid water. During the change of state from liquid to solid or liquid to gas there is no change in the chemical composition of water during these change of states.