Concept:Most metals are solid at room temperature, but a few metals have very low melting points and stay liquid.
Explanation:Ordinary temperature is usually taken as room temperature, around
25∘C.
Copper, gold, and silver all have high melting points, so they remain solid at this temperature.
Mercury, however, has a melting point of about
−39∘C, which is far below room temperature.
Therefore, mercury exists as a liquid at ordinary temperature.
Answer:C. Mercury