The overall cell reaction of the lead storage battery on discharge is
A{'text': 'Pb + PbO₂ + 2H₂SO₄ → 2PbSO₄ + 2H₂O', 'label': 'A'}
B{'text': 'PbO₂ + PbSO₄ + H₂O → Pb + H₂SO₄', 'label': 'B'}
C{'text': '2Pb + O₂ → 2PbO', 'label': 'C'}
D{'text': 'PbSO₄ + 4H₂O → Pb(OH)₄ + H₂SO₄', 'label': 'D'}
Answer & Solution
Correct answer: A. {'text': 'Pb + PbO₂ + 2H₂SO₄ → 2PbSO₄ + 2H₂O', 'label': 'A'}
1. Lead storage battery: Pb (anode, oxidised), PbO₂ (cathode, reduced).
2. Anode: Pb + SO₄²⁻ → PbSO₄ + 2e⁻.
3. Cathode: PbO₂ + SO₄²⁻ + 4H⁺ + 2e⁻ → PbSO₄ + 2H₂O.
4. Overall: Pb + PbO₂ + 2H₂SO₄ → 2PbSO₄ + 2H₂O. Both electrodes form PbSO₄ on discharge.
_Source: NCERT Class 12 Chemistry, Unit 3 "Electrochemistry", §3.6_
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