A blue solution of copper sulphate becomes darker when treated with excess of ammonia. This is because

Options

A. ammonia molecules replace water molecules in the solution
B. ammonia is stronger ligand than water
C. ammonia forms a stable complex ion `[Cu(NH_3 )_4]^(2+)` with `Cu^(2+)` ions
D. All are correct

Answer

D

Explanation

`[Cu underset("blue soln")((H_2 O) ] SO_4 . H_2 O + 4NH_45 OH to underset("dark blue soln")([Cu (NH_3)_4 ] SO_4 ) + 9 H_ 2O`