JEE Advanced · Chemistry · 20. Metallurgy

Match the extraction processes listed in column I with metals listed in column II.

A (A) P,S, (B) R, (C) P,Q, (D) P,S
B (A) Q,S, (B) R, (C) S, (D) S
C (A) P,R, (B) P, R, (C) Q, (D) R
D (A) P,R, (B) P, (C) Q, (D) S

Verified Solution

Answer & Solution

Correct Answer

(D) (A) P,R, (B) P, (C) Q, (D) S

Step-by-step Solution

Detailed explanation

Column I
Column II
(A) Self reduction $\left[\begin{array}{c}P \text { - Lead } \\ R \text { - Copper }\end{array}\right]$
$
\begin{aligned}
& \text { i.e., } A \rightleftarrows P \text { and } R \\
& \text { In lead metal } \\
& \qquad\left\{\begin{array}{c}
2 \mathrm{PbS}+3 \mathrm{O}_2 \longrightarrow 2 \mathrm{PbO}+2 \mathrm{SO}_2 \\
2 \mathrm{PbO}+\mathrm{PbS} \longrightarrow 3 \mathrm{~Pb}+\mathrm{SO}_2
\end{array}\right.
\end{aligned}
$
(self reduction)
In copper metal
$
\begin{aligned}
& 2 \mathrm{Cu}_2 \mathrm{~S}+3 \mathrm{O}_2 \longrightarrow 2 \mathrm{Cu}_2 \mathrm{O}+2 \mathrm{SO}_2 \\
& \mathrm{Cu}_2 \mathrm{~S}+2 \mathrm{Cu}_2 \mathrm{O} \longrightarrow 6 \mathrm{Cu}+\mathrm{SO}_2
\end{aligned}
$
(self reduction)
(B) Carbon reduction $P$-lead
$
\begin{aligned}
& \text { i.e., } \mathrm{B}-\mathrm{P} \\
& \text { In lead metal } \\
& \qquad \mathrm{PbO}+\mathrm{C} \longrightarrow \mathrm{Pb}+\mathrm{CO} \\
& \mathrm{PbO}+\mathrm{CO} \longrightarrow \mathrm{Pb}+\mathrm{CO}_2
\end{aligned}
$
Carbon reduction process is used for the reduction of oxides of electropositive metals like $\mathrm{Fe}, \mathrm{Pb}$ etc. This reduction is carried out with coal or coke on strongly heating.
(C) Complex formation and displacement by metal.
i.e., $C-Q$ (silver)

In silver metal
Argentite mineral of $\mathrm{Ag}\left(\mathrm{Ag}_2 \mathrm{~S}\right)$ is treated with $0.7 \% \mathrm{NaCN}$ solution in presence of air, therefore firstly sodium argento cyanide complex is formed which on heating with zinc metal, therefore by displacement silver is isolated.
$
\begin{aligned}
& \mathrm{Ag}_2 \mathrm{~S}+4 \mathrm{NaCN} \longrightarrow 2 \mathrm{Na}\left[\mathrm{Ag}(\mathrm{CN})_2\right]+\mathrm{Na}_2 \mathrm{~S} \\
& 2 \mathrm{Na}\left[\mathrm{Ag}(\mathrm{CN})_2\right]+\mathrm{Zn} \longrightarrow \mathrm{Na}\left[\mathrm{Zn}(\mathrm{CN})_4\right]+\underset{\text { Soluble }}{2 \mathrm{Ag}} \downarrow
\end{aligned}
$
(D) Decomposition of iodide-(S) Boron
$
\text { i.e., }(D)-(S)
$
By decomposition of iodide boron metal is isolated.

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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