UPSC Prelims 1995 · General Studies
Question 113: Science and Technology
Which one of the following pairs of materials serves as electrodes in chargeable batteries commonly used in devices such as torchlights, electric shavers, etc.?
AnswerThe answer is (a).
Rechargeable batteries used in torches and shavers are nickel-cadmium cells: the positive electrode is nickel oxyhydroxide and the negative is cadmium, in an alkaline electrolyte, and they can be recharged many times. Zinc-carbon cells are not rechargeable, and lead with lead peroxide is the car battery. Remember: Ni-Cd for small rechargeable devices, lead-acid for vehicles.
Why each option is right or wrong
- (a) Right: nickel and cadmium.
- (b) Zinc and carbon make the ordinary dry cell, which is not rechargeable.
- (c) Lead peroxide and lead are the electrodes of the lead-acid car battery.
- (d) Iron and cadmium is not the common pair; the nickel-iron cell uses nickel and iron.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1995, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.