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

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.

hope this

explanation:

covalent bonds

consist of pairs of electrons shared by two atoms, and bind the atoms to fixed orientation and requre high energies to break them

ionic bonds

when two atoms differ considerably in their electronegativity, then one of the atoms will lose its electron to the other atom. this results in a positively charged ion(cation) and a negatively charged ion (anion)

the product of the pressure and volume is also constant