Question

Native silver metal forms a water soluble complex with a dilute aqueous solution of $NaCN$ in the presence of

• A. nitrogen
• B. oxygen
• C. carbon dioxide
• D. argon

Answer 1

Answer: (B)

oxygen

Answer 2

A water soluble complex with silver and dilute aqueous solution of NaCN is $Na[Ag(CN)_2)$ In the cyanide process, the native silver is crushed and treated with aqueous NaCN solution and aerated.
$4Ag+8NaCN+2H_2O+O_2\rightarrow 4Na[Ag(CN)_2]+4NaOH$