Question

A bulb of a thermometer is placed in your mouth. Which of the following explains why the level of the liquid rises in the thermometer?

hot air rises in the thermometer
heat energy changes into light energy

heat can change a solid to a liquid
the liquid expands when heated

Answer 1

The answer is the last option

The liquid expands when heated.

Answer 2

Answer: the liquid expands when heated

Step-by-step explanation:

The coefficient of thermal expansion of mercury is higher than the glass contained and its the only metal that is liquid at room temperature. These characteristics let us use it to read a change of temperature in a termometer as you can see in the image below.