Question

The active material used in lead acid battery are
\[
  {\text{a}}{\text{. spongy lead and lead oxide}} \\
  {\text{b}}{\text{. lead oxide and P}}{{\text{b}}_2}{{\text{O}}_2} \\
  {\text{c}}{\text{. spongy lead and P}}{{\text{b}}_2}{O_3} \\
  {\text{d}}{\text{. only lead oxide}} \\
 \]

Answer 1

Hint: Lead storage batteries are designed for automobile engines and they can’t afford deep discharge. They have a large number of thin plates which accounts for increase in surface area and therefore maximum current is generated which is damaged by deep discharge.

Complete answer:
The different type of batteries on the basis of whether they are rechargeable or not are as follows:
Primary battery: are those in which redox reaction occurs only once and the cell becomes dead after sometimes example dry cell, mercury cells.
Secondary cells are those which can be recharged by passing an electric current through them and hence can be used over and again. Example is lead acid battery.
In the charged state, the battery's chemical energy is stored in potential energy. It is between the pure lead which is at the negative side and at cathode will be the grid of lead packed with lead oxide. The electrolyte is formed by diluted Sulphuric acid. The reaction occurring during discharging-
Cathode reaction:
\[Pb{O_2} + 4{H^ + } + 2{e^ - } \to P{b^{2 + }} + 2{H_2}O\] (reduction)
\[P{b^{2 + }} + S{O_4}^{2 - } \to PbS{O_4}\] (precipitation)
\[net:Pb{O_2} + 4{H^ + } + 2{e^ - } + S{O_4}^{2 - } \to PbS{O_4} + 2{H_2}O\]
The energy produced during discharging of lead acid battery can be attributed to the energy released when the strong chemical bonds of water molecules are formed from \[{H^ + }\] ions of the acid and \[{O^{ - 2}}\] ions of \[Pb{O_2}\].
Anodic reaction:

\[Pb \to P{b^{2 + }} + 2{e^ - }{\text{ (oxidation)}}\]
\[P{b^{2 + }} + S{O_4}^{2 - } \to PbS{O_4}{\text{ (precipitation)}}\]
\[net:{\text{ }}Pb{O_2} + S{O_4}^{2 - } \to PbS{O_4} + 2{e^ - }\]
Sulphuric acid is consumed during discharging and when the concentration of the same falls, it requires recharging.
In recharging current is passed from outside source to reverse the reactions of anode and cathode till the concentration of sulphuric again raises.
Thus the answer is spongy lead and lead oxide.

Note:
Lead storage battery is a reversible cell functioning as electrochemical cell during discharging and as electrolytic cell during recharging. There is one more type of secondary cell which is nickel cadmium cell and has longer life than lead acid battery.