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NEET levelSingle correct optionDifficulty 1 of 3ec152

In a lead storage battery, which of the following happens during discharge?

AThe density of the electrolyte decreases
B $PbO X_{2}$ is formed at the cathode
CMetallic lead is formed at the anode
DThe concentration of $H X_{2} SO X_{4}$ increases

Answer: A

Discharge reaction:

Pb + PbO X_{2} + 2 H X_{2} SO X_{4} 2 PbSO X_{4} + 2 H X_{2} O

. Sulphuric acid is consumed and water is formed, so the acid concentration and hence the density of the electrolyte fall; this is why the state of charge is checked with a hydrometer. Both electrodes are converted to

PbSO X_{4}

;

Pb

and

PbO X_{2}

are regenerated only during charging.

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