An efflorescent compound is a substance that?

A.

absorbs water froom the air without dissolving in it

B.

is capable of giving off coloured luminosity

C.

gives out water to the atmosphere

D.

absorbs water from the air and dissolves in it

E.

gives out its water of crystallization on heating

Correct answer is C

Efflorescence is a phenomenon where a crystalline salt loses all or part of its water of crystallization when exposed to the atmosphere to form a lower dehydrate or an anhydrous salt.