Physics 5054 · O Level · Melting, boiling and evaporation
Melting, boiling and evaporation — practice question
A beaker of water is set on an electric hotplate and heated until it boils. While boiling, the water changes from a liquid to a gas.
(a)[3]
Describe, in terms of the molecules, three differences between a gas and a liquid.
(b)[2]
To keep the liquid boiling, the hotplate has to remain switched on. Explain why energy must be supplied to change a liquid at its boiling point into a gas.
Worked solution & mark scheme
This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “The molecules are farther apart” …