Question

$C{N}^{\ominus }$ solution used in extraction of which

• A. Ag
• B. Ti
• C. Zn
• D. Sn

Answer 1

Answer: (A)

$C{N}^{-}$ion is used in the extraction of silver (Ag) metal. Since, silver is precipitated by complex formation.
Powered argentite $(A{g}_{2}S$ ) is lixivated with dil. $NaCN$ solution in presence of air.
$A{g}_{2}S+4NaCN\stackrel{\text{ air }}{\to }\underset{\stackrel{\text{Argentocyanide }}{\text{(complex salt)}}}{2Na\left[Ag(CN{)}_2\right]}+N{a}_{2}S{O}_4$
To, this complex salt metallic zinc is added.
$2Na\left[Ag(CN{)}_2\right]+Zn⟶N{a}_2\left[Zn\left(C{N}_4\right)(\text{ aq })\right]+\underset{\text{Black ppt}}{2Ag}$