Describe one example each of expansion in solids, liquids and gases.

Expansion of solid: Solids also undergo thermal expansion. Railroad tracks and bridges, for example, have expansion joints to allow them to freely expand and contract with temperature changes.  

Expansion of liquid: Heating of water expands it and converts it to gas

Expansion of gas: When a balloon is partially inflated in a cool room it expands to full size when put in warm water. This all is due to thermal expansion. So, an increase in the dimension of a body due to an increase in temperature is thermal expansion