In a solution containing `Cu^(2+)` and `Cd^(2+)` dil. `H_(2)SO_(4)` is added followed by iron filings. The solution is warmed and `NH_(4)OH` is added to reduce the acidity followed by passing of `H_(2)S` gas. The ppt. obtained will be

Options

A. CuS only
B. CdS only
C. Both Cu metal and CdS
D. CuS, CdS and `FeSO_4`

Answer

C

Explanation

`Cu^(2+)` ion from solution is removed completely by precipitation with iron filing because iron is more electroposition than copper `(Cu^(+2) + Fe to Fe^(+2) + Cu)` . On passing `H_2 S`, a yellow ppt. of CdS is obtained . Thus the precipitate contain both Cu metal and CdS.