Question

Why solids expand on heating
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Answer 1

Explanation:

When a solid is heated, its atoms vibrate faster about their fixed points. The relative increase in the size of solids when heated is therefore small. ... Liquids expand for the same reason, but because the bonds between separate molecules are usually less tight they expand more than solids.

Answer 2

All three states of matter (solid, liquid and gas) expand when heated. The atoms themselves do not expand, but the volume they take up does. When a solid is heated, its atoms vibrate faster about their fixed points. ... An increase in temperature results in the expansion of the liquid which means it rises up the glass.

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