CBSE Class 12-science Answered

1. In case of lead storage batteries, the battery contains a diluted sulphuric acid electrolyte and positive and negative electrodes in the form of several plates. These plates are each connected together by separate plate straps. These groups of plates and the seperators assembled together form the battery cell element. Grouping the plates in this way and keeping them in a single compartment serves to enlarge the surface area between the active materials and the electrolyte thus allowing a greater amount of electricity to be supplied i.e. the battery capacity is increased because of increase in surface area. More surface area means the battery can deliver more current.

2. As batteries are charged, a small quantity of water in the electrolyte is broken down into hydrogen and oxygen by the charging current. The gases are dissipated through openings in vent plugs. As this process takes place, electrolyte level gradually lowers until distilled water must be added. Hence, these lead storage batteries require water replacement.