CUET · CHEMISTRY · PYQ PAPER 2023

Which of the following reaction occurs at anode during discharging of lead storage battery?

A \(PbO_2(s) + SO_4^{2-}(aq) +4H^+(aq) + 2e^- \rightarrow PbSO_4(s) + 2H_2O(l)\)
B \(Pb(s) + SO_4^{2-}(aq) \rightarrow PbSO_4(s) + 2e^-\)
C \(PbSO_4 + 2e^- \rightarrow Pb(s) + SO_4^{2-}(aq)\)
D \(PbSO_4(s) + 2H_2O(l) \rightarrow PbO_2(s) + Pb(s) + 2H_2SO_4 + SO_4^{2-}(aq) + H^+(aq) + 2e^-\)

Verified Solution

Answer & Solution

Correct Answer

(B) \(Pb(s) + SO_4^{2-}(aq) \rightarrow PbSO_4(s) + 2e^-\)

Step-by-step Solution

Detailed explanation

\(Pb(s) + SO_4^{2-}(aq) \rightarrow PbSO_4(s) + 2e^-\)

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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