The cyanide process of gold extraction involves leaching out gold from its ore with ${\mathrm{C}\mathrm{N}}^{-}$ in the presence of $\mathrm{Q}$ in water to form $\mathrm{R}$ . Subsequently, $\mathrm{R}$ is treated with $\mathrm{T}$ to obtain $\mathrm{A}\mathrm{u}$ and $\mathrm{Z}$ . Choose the correct option(s).

• Correct answer
  A

  $\mathrm{T}$ is $\mathrm{Z}\mathrm{n}$
• B

  $\mathrm{R}$ is ${\left[\mathrm{A}\mathrm{u}{\left(\mathrm{C}\mathrm{N}\right)}_4\right]}^{-}$
• Correct answer
  C

  $\mathrm{Z}$ is ${\left[\mathrm{Z}\mathrm{n}{\left(\mathrm{C}\mathrm{N}\right)}_4\right]}^{2-}$
• Correct answer
  D

  $\mathrm{Q}$ is ${\mathrm{O}}_2$

Hence, the correct answer is options: 'A', 'C', 'D'.