Question

For a car battery which one is the correct statement?
A: Cathode is lead dioxide $\left( {Pb{O_2}} \right)$ and anode is copper $\left( {Cu} \right)$.
B: Cathode is copper $\left( {Cu} \right)$ and anode is lead dioxide $\left( {Pb{O_2}} \right)$.
C: Cathode is copper $\left( {Cu} \right)$ and anode is lead $\left( {Pb} \right)$.
D: Cathode is lead dioxide $\left( {Pb{O_2}} \right)$ and anode is lead $\left( {Pb} \right)$.

Answer 1

Hint: There are two electrodes, anode and cathode. Anode is the electrode where oxidation occurs and cathode is the electrode where reduction occurs. Battery anode is always negative and cathode is positive.

Complete step by step answer:
There are two electrodes in the car battery that are cathode and anode. Anode is that electrode where oxidation occurs and cathode is that electrode where reduction occurs. Oxidation refers to loss of electrons and reduction refers to gain of electrons. Battery anode is always negative and battery cathode is always positive. Anode electrode releases electrons during discharge and cathode electrons absorb these electrons.

Batteries used in cars are lead-acid batteries. This battery is rechargeable. Car battery consists of six electrochemical cells. These cells are connected in series. Anode of each cell is made of lead and cathode of each cell is made of lead dioxide. These electrodes (lead at anode and lead dioxide at cathode) are immersed in sulphuric acid solution.

Reaction that takes place at anode is:
$Pb + {H_2}S{O_4}\xrightarrow[{}]{}PbS{O_4} + 2{H^ + } + 2{e^ - }$
Reaction that takes place at cathode is:
$Pb{O_2} + {H_2}S{O_4} + 2{e^ - } + 2{H^ + }\xrightarrow[{}]{}2{H_2}O + PbS{O_4}$
So, the correct answer is option D that is cathode is lead dioxide $\left( {Pb{O_2}} \right)$ and anode is lead $\left( {Pb} \right)$.

Additional information: Rechargeable batteries are also called secondary cells and non-rechargeable batteries are called primary cells. Some rechargeable batteries are aluminum-ion battery, carbon battery, lead-acid battery, glass battery, lithium-ion battery etc.


Note:
Electrolytic cell is that cell which uses electric energy to make a non-spontaneous redox reaction, spontaneous. Voltaic cell or galvanic cell is that cell which derives electrical energy from a spontaneous reaction that is taking place in the cell.