The correct answer is B. Nickel and cadmium.
Nickel-cadmium (NiCd) batteries are a type of rechargeable battery that is commonly used in devices such as torch lights, electric shavers, and power tools. They are known for their high capacity and long life.
The electrodes in a NiCd battery are made of nickel and cadmium. The anode is made of nickel oxide, and the cathode is made of cadmium. The electrolyte is a solution of potassium hydroxide.
When the battery is discharged, the nickel oxide at the anode is reduced to nickel metal, and the cadmium at the cathode is oxidized to cadmium oxide. The electrolyte is also consumed during the discharge process.
When the battery is recharged, the reverse reaction occurs. The nickel metal at the anode is oxidized to nickel oxide, and the cadmium oxide at the cathode is reduced to cadmium metal. The electrolyte is also produced during the recharge process.
NiCd batteries are a reliable and efficient source of power. However, they have a number of disadvantages. One disadvantage is that they have a memory effect. This means that if a NiCd battery is not fully discharged before it is recharged, it will lose capacity. Another disadvantage is that NiCd batteries can be damaged by deep discharge. This means that if a NiCd battery is discharged below a certain level, it can be permanently damaged.
Despite these disadvantages, NiCd batteries are still a popular choice for many applications. They are relatively inexpensive, and they have a long life. They are also relatively safe to use.
The other options are incorrect because they do not represent the electrodes in a NiCd battery.
Option A: Iron and cadmium are not the electrodes in a NiCd battery. The anode is made of nickel oxide, and the cathode is made of cadmium.
Option C: Lead peroxide and lead are the electrodes in a lead-acid battery.
Option D: Zinc and carbon are the electrodes in a zinc-carbon battery.