UPSC Prelims 2013 · GS Paper I
Question 95: Science and Technology
The known forces of nature can be divided into four classes, viz., gravity, electromagnetism, weak nuclear force and strong nuclear force. With reference to them, which one of the following statements is not correct?
AnswerUPSC’s answer is (a).
Gravity is the weakest of the four fundamental forces, by a very large factor; it seems strong only because it always attracts, acts over long distances and the masses involved are huge. Electromagnetism acts on charged particles, the weak force causes radioactive beta decay, and the strong force binds protons and neutrons in the nucleus. The statement that gravity is the strongest is the one that is not correct.
Why each option is right or wrong
- (a) Correct choice. Gravity is the weakest of the four forces, so this statement is not correct.
- (b) True statement. Electromagnetism acts on electrically charged particles.
- (c) True statement. The weak force is behind radioactive decay.
- (d) True statement. The strong force holds the nucleus together.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2013, General Studies Paper I, Series A. The paper on upsc.gov.in.