`CuSO_(4).5H_(2)O` is blue in colour because

Options

A. It contains water of crystallization
B. `SO_(4)^(2-)` ions absorb red light
C. `Cu^(2+)` ions absorb red light
D. `Cu^(2+)` ions absorb all colours except red from the white light.

Answer

C

Explanation

`Cu^(+)`ion `(3d^9)` absorbs red light from the visible region, for the promotion of 3d electrons, the ions reflect blue light and appear blue.