An aqueous solution of gas (X) shows the following reactions. (i) It turns red litmus blue.
(ii) When added in excess to a copper sulphate solution, a deep blue colour is obtained.
(iii) On addition of `FeCl_(3)` solution, a brown precipitate , soluble in dilute `HNO_(3)` is obtained.
Identify (X) and give equations for the reactions at step (ii) and (iii).

Explanation

Gas 'X' is soluble in water forming basic solution because it turns red litmus blue. Hence, the gas may be `NH_(3). NH_(3)+H_(2)OrarrNH_(4)OH`
`CuSO_(4)+4NH_(4)OH rarr underset("Deep blue complex")underset(("Tetraammine cupric sulphate"))( [Cu(NH_(3))_(4)]SO_(4))+4H_(2)O`
Ferric chloride gives brown precipitate of `Fe(OH)_(3)`.
`FeCl_(3)+3NH_(4)OHrarr underset(("Brown precipitate"))(Fe(OH)_(3))+3NH_(4)Cl`
Brown precipitate is soluble in `HNO_(3)`.
`Fe(OH)_(3)+3HNO_(3)rarrunderset(("Soluble complex"))(Fe(NO_(3))_(3))+3H_(2)O`