Explanation

(b)
A water soluble complex of silver with a dilute aqueous solution of NaCN is sodium argentocyanide, in the cyanide process, the native from is crushed and treated with 0.1-0.2% solution of NaCN and aerated
$4Ag + 8NaCN + 2H_{2}O + O_{2} \rightarrow 4Na\left\lbrack Ag(CN)_{2} \right\rbrack + 4NaOH$
Argentocyanide is soluble metal is recovered from the complex by reduction with zinc