Question

why do mercury expands

Answer 1

When materials gain heat energy, theyexpand. This is because the atoms that comprise these materials have more energy and vibrate more. Almost all materials expand when heated, not just the mercury or alcohol in thermometers.

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Answer 2

when the temperature raises the mercury expand, causing the bird to dip down once again when any substance is heated it's bulk almost always increases in the other whether it is solid, a liquid gas it expands on heating.

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