Equal masses of two different liquids, Liquid X and Liquid Y, are initially at $15^{\circ }C$. Each liquid is heated in separate insulated containers using identical $50W$ electrical heaters.

• For Liquid X, the temperature initially rises at a rate of $1.5^{\circ }C$ per minute, and eventually the temperature stops rising at $78^{\circ }C$.
• For Liquid Y, the temperature initially rises at a rate of $3.0^{\circ }C$ per minute, and eventually the temperature stops rising at $180^{\circ }C$.

State and explain: (i) which liquid, Liquid X or Liquid Y, has the higher boiling point; (ii) which liquid has the greater thermal capacity.

A metal-cased electric heater is mounted on the wall of a cold room near the floor. (i) State the name of the process by which thermal energy passes through the metal casing of the heater. (ii) State the two main processes by which thermal energy is transferred from the outside surface of the heater to the rest of the room. (iii) Describe the movement of the air in the room and explain how this movement transfers thermal energy throughout the entire room.