When ZnS and PbS minearls are present together, then NaCN is added to separate them in the froth floatation process as a depressant, because :

Options

A. `Pb(CN)_(2)` is precipitated while no effect on ZnS
B. ZnS forms soluble complex `Na_(2)[Zn(CN)_(4)]`
C. PbS forms soluble complex `Na_(2)[Pb(CN)_(4)]`
D. They cannot be separated by adding NaCN

Answer

B

Explanation

`ZnS+4NaCN hArr 4Na^(+) + underset("water soluble")([Zn(CN)_(4)]^(2-))+S^(2-)`