1. Recall the construction and working of a lead storage battery

A lead storage battery contains:

• Positive plate: lead dioxide, $\mathrm{PbO_2}$
• Negative plate: spongy lead, $\mathrm{Pb}$
• Electrolyte: about $38\%$ sulphuric acid solution

So statement D is correct.

Also, in many standard JEE texts, the anode is taken as the positive plate during charging, and the battery is described as consisting of a lead grid packed with $\mathrm{PbO_2}$ as anode. Hence statement C is also taken as correct in this context.

2. What happens during discharge?

During discharge, both plates get converted into lead sulfate:

At anode (negative during discharge):

At cathode (positive during discharge):

Thus, after discharge both electrodes become coated with $\mathrm{PbSO_4}$.

3. What happens during charging?

Charging reverses the discharge reactions.

• The $\mathrm{PbSO_4}$ on one plate is converted back to Pb.
• The $\mathrm{PbSO_4}$ on the other plate is converted back to PbO$_2$.

Specifically:

• On the cathode during charging, reduction occurs and $\mathrm{PbSO_4}$ is converted to $\mathrm{Pb}$, not $\mathrm{PbO_2}$.
• On the anode during charging, oxidation occurs and $\mathrm{PbSO_4}$ is converted to $\mathrm{PbO_2}$.

So, chemically:

• A is true
• B is false

4. Now evaluate each statement

Statement A

During charging, $\mathrm{PbSO_4}$ on anode is converted into $\mathrm{PbO_2}$.

This is correct.

Statement B

During charging, $\mathrm{PbSO_4}$ on cathode is converted into $\mathrm{PbO_2}$.

This is incorrect; it is converted into $\mathrm{Pb}$.

Statement C

Lead storage battery consists of grid of lead packed with $\mathrm{PbO_2}$ as anode.

This is taken as correct in the standard construction description.

Statement D

Lead storage battery has about $38\%$ solution of sulphuric acid as electrolyte.

This is correct.

5. Correct combination

The correct statements are:

But this combination is not present in the options.

Now compare with given options:

• Option A: $A, B, D$ only $\to$ wrong because $B$ is false
• Option B: $B, C$ only $\to$ wrong because $B$ is false
• Option C: $B, C, D$ only $\to$ wrong because $B$ is false
• Option D: $B, D$ only $\to$ wrong because $B$ is false and $A$ is true

So the listed options are inconsistent with the chemistry.

6. Comparison with stored answer

Stored correct answer: D

But option D = B, D only, which includes statement $B$, and statement $B$ is chemically incorrect.

Hence I do not agree with the stored answer.