Question

On cooling, liquid changes into a solid state. Give reason.

Answer 1

Increasing heat change in the state of matter

• Heating the matter increases the energy of particles whereas cooling the matter decreases the energy of particles.
• This change in energy brings a change in the state of matter.
• Solids change into liquids, and liquids into gases when particles of matter gain more kinetic energy.

Decreasing heat (cooling)

• The reverse of the above process occurs during the cooling of the gas.
• When heat is taken away from gas, the kinetic energy of its particle reduces, thus decreasing the inter-particle spaces.
• This leads to an increase in the inter-particle force of attraction.
• If the cooling process continues, eventually the gaseous state changes to the liquid state. On further cooling, the liquid state changes to the solid state.

$\mathrm{Solid}\underset{\mathrm{Cooling}}{\overset{\mathrm{Heating}}{\rightleftharpoons }}\mathrm{Liquid}$