Question 42

For lead storage battery pick the correct statements
A. During charging of battery, PbSO$$_4$$ on anode is converted into PbO$$_2$$
B. During charging of battery, PbSO$$_4$$ on cathode is converted into PbO$$_2$$
C. Lead storage battery consists of grid of lead packed with PbO$$_2$$ as anode
D. Lead storage battery has ~38% solution of sulphuric acid as an electrolyte
Choose the correct answer from the options given below:

Solution

A lead storage battery is a secondary cell (rechargeable).
To evaluate the statements, we analyze its composition and chemical processes during discharging and charging cycles.

1. Battery Construction (Standard State)

Anode: Spongy Lead ($$Pb$$).
Cathode: A grid of lead packed with Lead Dioxide ($$PbO_2$$).
Electrolyte: An aqueous solution of Sulphuric Acid ($$H_{2}SO_4$$), approximately 38% by mass (density ≈ 1.30 g/mL).

2. Chemical Reactions During Charging

During the charging process, an external electrical source reverses the spontaneous cell reactions. The $$PbSO_4$$ deposited during discharge is converted back:

At Anode (Reduction during charging):

$$PbSO_4(s)+2e^-→Pb(s)+SO_4^{2-}(aq)$$

At Cathode (Oxidation during charging):

$$PbSO_4(s)+2H_2O(l)→PbO_2(s)+SO_4^{2-}(aq)+4H^+(aq)+2e^-$$

Statement	Analysis	Status
A	During charging, PbSO4 on the anode is reduced back to spongy lead (Pb), not PbO2.	Incorrect
B	During charging, PbSO4 on the cathode is oxidized to Lead Dioxide (PbO2).	Correct
C	The grid packed with PbO2 acts as the cathode, while the grid packed with spongy lead serves as the anode.	Incorrect
D	A standard lead storage battery uses a ~38% H2SO4 solution as its electrolyte environment.	Correct

Final Conclusion

Statements B and D are completely precise and scientifically accurate based on core electrochemical principles.

Correct Answer: B, D only

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