MHT CET202526 Apr 2025Morning ShiftChemistryElectrochemistryActual
Which of the following changes takes place at positive electrode during recharging of lead accumulator?
Options
- APb is oxidised to PbSO ₄
- BPbSO ₄ is oxidised to PbO ₂
- CPbSO ₄ is reduced to Pb
- DPbO ₂ is reduced to PbSO ₄
Correct answer
B. PbSO ₄ is oxidised to PbO ₂
Step-by-step solution
The lead accumulator's recharging process involves reversing the discharge reactions. During discharge, the positive electrode (cathode) undergoes reduction: PbO ₂(s) + SO ₄²⁻(aq) + 4 H ^+(aq) + 2e^- PbSO ₄(s) + 2 H ₂ O (l) Upon recharging, this electrode becomes the anode. The reverse oxidation reaction occurs: PbSO ₄(s) + 2 H ₂ O (l) PbO ₂(s) + SO ₄²⁻(aq) + 4 H ^+(aq) + 2e^- This corresponds to oxidation of PbSO ₄ to PbO ₂ , matching option B.