Question

The metal extracted by leaching with cyanide is:

• A. $\mathrm{Cu}$
• B. $\mathrm{Mg}$
• C. $\mathrm{Na}$
• D. $\mathrm{Ag}$

Answer 1

The correct option is D

$\mathrm{Ag}$

Explanation for correct options

(D) $\mathrm{Ag}$

Leaching

• Leaching is defined as the process of extraction of metals from their ore with the help of a solvent.
• In this process, Silver ($\mathrm{Ag}$) and Gold ($\mathrm{Au}$) can be extracted from their respective metal ores with the help of dilute solutions of Sodium cyanide ($\mathrm{NaCN}$) or Potassium cyanide ($\mathrm{KCN}$) in presence of Oxygen (${\mathrm{O}}_2$).
• The chemical reactions involved in the extraction process are shown below:
• $$\begin{gathered} 4\mathrm{Ag}\left(\mathrm{s}\right)+8{\mathrm{CN}}^{-}\left(\mathrm{aq}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{aq}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 4{\left[\mathrm{Ag}{\left(\mathrm{CN}\right)}_2\right]}^{-}\left(\mathrm{aq}\right)+4{\mathrm{OH}}^{-}\left(\mathrm{aq}\right) \\ 2{\left[\mathrm{Ag}{\left(\mathrm{CN}\right)}_2\right]}^{-}\left(\mathrm{aq}\right)+\mathrm{Zn}\left(\mathrm{s}\right)\to {\left[\mathrm{Zn}{\left(\mathrm{CN}\right)}_4\right]}^{2-}\left(\mathrm{aq}\right)+2\mathrm{Ag}\left(\mathrm{s}\right) \end{gathered}$$

Explanation for incorrect options

The metal extracted by leaching with cyanide is silver and gold. Hence, options (A), (B), and (C) are incorrect.

Hence, option (D) is correct. The metal extracted by leaching with cyanide is $\mathrm{Ag}$.