When the temperature rises, the liquid in the thermometer <u>expands.</u> When the temperature drops, the liquid in the thermometer <u>contracts</u>.
Explanation:
The thermometer is filled with a liquid called mercury. Increase in temperature makes this liquid to expand. The expanded liquid occupies most of the space in the thermometer causing a rise in its level.
On the other hand, a drop in temperature makes the liquid to contract. The contracted liquid has less volume and occupies lesser space in thermometer. This causes a drop in the level of liquid in thermometer.
