What compound do the positive and negative plates of a discharged battery primarily convert into?

The correct answer is lead sulfate (PbSO4) because, during the discharge process of a lead-acid battery, the electrochemical reactions lead to the conversion of lead dioxide (PbO2) on the positive plate and sponge lead (Pb) on the negative plate into lead sulfate. This reaction is a fundamental part of how lead-acid batteries operate. When the battery discharges, electrical energy is produced through the transformation of these materials into lead sulfate, which accumulates on the plates.

In addition, sulfuric acid (H2SO4) is present in the electrolyte solution, and while it plays a critical role in the battery's operation, it does not convert into a solid compound like lead sulfate during the discharge cycle. Water may be produced as a byproduct of certain reactions in batteries but is not the primary conversion product of the battery plates. Therefore, lead sulfate is the primary compound formed from the discharged state of the battery plates.