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Topic: metal

which metal does not expand when heated?

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Re: metal

All metals (including mercury which is only metal found in liquid state at atmospheric temperature) expand with application of heat. Hence answer to your question is "no any metal'.

But
Silicon (which is Metalloid  and not a metal), exhibit  negative temp coefficient (means contracts after application of heat) between 18 deg K and 120 degree K.
Zirconium tungstate (which is metal oxide) shows negative temp in wide temp range of 0.3 to 1050 K