Question

How liquid in a thermometer changes so that it can be used to measure temperature

Answer 1

Most liquids expand when they are heated and contract when they are cooled.

A thermometer consists of a bulb of liquid connected to a thin capillary tube.

When the liquid is heated, it expands and moves up the capillary column. When the liquid cools, it contracts and moves back down the column.

You can determine the temperature by reading the position of the liquid against a graduated temperature scale.

Answer 2

Answer

Liquid in thermometer chnages on the basis of changing temperature

Explanation

Mercury is the most commonly used liquid in a thermometer. The thermometric property of mercury is that it expand or contract with change in temperature. With a rise in temperature, the liquid gets heated and expand and when temperature reduces, the liquid moves down to the tube. This thermometric property  of mercury is used to measure temperature.