1. Extended Tier Only

Liquids and gases are two states of matter.

In both boiling and evaporation, a liquid changes into a gas.

(i)  State two ways in which boiling differs from evaporation.

[2]

(ii) Before injecting a patient, a doctor wipes a small amount of a volatile liquid on to the patient’s skin.

Explain, in terms of molecules, how this procedure cools the patient’s skin.

[4]