Which one of the following metals is liquid at ordinary temperature?

The correct answer is (c), Mercury. Mercury is the only metal that is liquid at ordinary temperature (20°C). It is a silvery-white metal that is highly reflective and has a very low melting point. Mercury is used in a variety of applications, including thermometers, barometers, and switches.

Lead is a heavy, soft, and malleable metal that is used in a variety of applications, including batteries, ammunition, and pipes. Lead has a melting point of 327.46°C.

Nickel is a hard, silvery-white metal that is used in a variety of applications, including coins, jewelry, and stainless steel. Nickel has a melting point of 1455°C.

Tin is