A) NaCN causes reduction by precipitation
B) A soluble complex is formed by reaction between NaCN and ZnS while PbS forms froth
C) A soluble complex is formed by reaction between NaCN and PbS while ZnS forms froth
D) A precipitate of \[Pb{{(CN)}_{2}}\] is produced while ZnS remain unaffected.
Correct Answer: B
Solution :
[b] \[NaCN+ZnS\xrightarrow{{}}\underset{Soluble\text{ }complex}{\mathop{N{{a}_{2}}\left[ Zn{{\left( CN \right)}_{4}} \right]}}\,\] A layer of this zinc complex is formed on the surface of ZnS and due to this ZnS is prevented from the froth formation while PbS form froth. (i.e, NaCN is added as depressant for ZnS)You need to login to perform this action.
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