Assertion : Cuprous ion ` (Cu^(+))` is colouless whereas cupric ion `(Cu^(++))` is blue in the aqueous solution.
Reason : Cuprous ion `(Cu^(+))` has unpaired electrons while cupric ion `(Cu^(++))` does not .

Options

A. If both the assertion and reason are true and reason is correct explanation of the assertion .
B. If both the assertion and reason are true but reason is not a correct explanation of the assertion .
C. If the assertion is true but the reason is false.
D. If both assertion and reason are false.

Answer

C

Explanation

Cuprous ions ` (Cu^(+))` is colourless because it has no unpaired electrons in the 3d sub-shell as it has ` 3d^(10)` configuration . The cupric ion ` (Cu^(++))` has one unpaired electron as it has configuration ` 3d^(9)` . By absorbing the visible light the unpaired electron can migrate from one set of d-orbitals to another under the applied field of water molecules. Hence cupric ion `(Cu^(++))` in aqueous solution shows blue colour.