UPSC Prelims 1999 · General Studies
Question 112: Science and Technology
Consider the following statements regarding a motor car battery: I. The voltage is usually 12 V. II. Electrolyte used is hydrochloric acid. III. Electrodes are lead and copper. IV. Capacity is expressed in ampere-hour. Which of the above statements are correct?
AnswerThe answer is (d).
A car (lead-acid) battery usually gives 12 V from six 2-volt cells, and its capacity is expressed in ampere-hours (I and IV). Its electrolyte is dilute sulphuric acid, not hydrochloric acid, and its plates are lead and lead dioxide, with no copper. Remember: 12 V, dilute sulphuric acid, lead and lead dioxide plates, ampere-hour.
- I. The voltage is usually 12 V.
- II. The electrolyte is dilute sulphuric acid, not hydrochloric acid.
- III. The electrodes are lead and lead dioxide, not copper.
- IV. Battery capacity is expressed in ampere-hours.
Why each option is right or wrong
- (a) Wrong. II is false: the electrolyte is sulphuric acid.
- (b) Wrong. II and III are both false.
- (c) Wrong. III is false: the plates are lead and lead dioxide.
- (d) Right. I and IV are correct.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1999, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.