Question

In the Mac. Arthur process of extraction

• A. R is ${\left[\mathrm{Au}\right({\mathrm{CN}}_4\left)\right]}^{-}$
• B. Z is $[\mathrm{Zn}{\left(\mathrm{CN}\right)}_4{]}^{2-}$
• C. Q is ${\mathrm{O}}_2$
• D. Y is $\mathrm{Zn}$

Answer 1

The correct option is D

Y is $\mathrm{Zn}$

The explanation for the correct answer.

• $\mathrm{Au}$ leached within$\mathrm{NaCN}$in the presence of air when gold and its salt are converted to soluble complex.
• $4\mathrm{Au}+8\mathrm{NaCN}+{\mathrm{O}}_2+2{\mathrm{H}}_2\mathrm{O}\to 4\mathrm{Na}{\left[\mathrm{Au}{\left(\mathrm{CN}\right)}_2\right]}^{}+4\mathrm{NaOH}$
• Zinc dust is then added to the precipitate$\mathrm{Au}$.
• ${2\mathrm{Na}\left[\mathrm{Au}\right({\mathrm{CN}}_2\left)\right]}^{-}+\mathrm{Zn}\to {\mathrm{Na}}_2[\mathrm{Zn}{\left(\mathrm{CN}\right)}_4{]}^{2-}+2\mathrm{Au}$
• $\mathrm{Au}$ react with $\mathrm{NaCN}$ and ${\mathrm{O}}_2$ to form ${\left[\mathrm{Au}\right({\mathrm{CN}}_4\left)\right]}^{-}$ which further react with $\mathrm{Zn}$ to form$[\mathrm{Zn}{\left(\mathrm{CN}\right)}_4{]}^{2-}$.

Hence the correct options are (B), (C), and (D).