Question

Explain how the liquid in a thermometer changes so that it can be used to measure a temperature

Answer 1

See..actually it is dependent on thermometer type,the glass tube of the thermometer is filled with either alcohol or Mercury and when it gets hotter, the liquid get heated and expands and rise up taking up more space inside the tube. and when it get colder, the liquid compacts and moves down the tube.
This rise and fall of the liquid , indicates the temperature.

Answer 2

The thermometer contains alcohol or methyl when it get heated it raise the temperature up and when it cools down it becomes normal(alcohol or methyl )