On adding excess of `NH_(3)` solution to `CuSO_(4)` solution, the dark blue colour is due to

Options

A. `[Cu(NH_3)_4]^(++)`
B. `[Cu(NH_3)_2]^(++)`
C. `[Cu(NH_3)]^(+)`
D. None of the above

Answer

A

Explanation

`CuSO_4 + 4NH_3 to [Cu (NH_3)_4]^(+ +) SO_4^(- -)` .