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

Options

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

Answer

C

Explanation

`Cu^(2+)` ion `(3d^(9))` absorbs red light from the visible region, for the promotion of `3d` electrons, the ions reflect blue and appear blue.