An aqueous solution of a gas (X) -turns red litmus blue. When excess of this solution is added to copper sulphate solution, it turns deep blue. When this solution is added to `FeCl_(3)` solution, a brownish precipitate soluble in `HNO_(3)` is obtained. Identify the gas (X) and write balanced equations for each of the reaction involved.

Explanation

These observations suggest that the gas (X) is ammonia `(NH_(3))` . In aqueous solution, it forms `NH_(4)OH` which turns red litmus paper blue. The reactions taking place are as follows:

`FeCl_(3)+3NH_(4)OHtoFe(OH)_(3)darr("brown")+3NH_(4)Cl`
`Fe(OH)_(3)+3HNO_(3)toFe(NO_(3))_(3)("soluble")+3H_(2)O`