UPSC Prelims 2020 · GS Paper I
Question 99: Geography
Consider the following statements :
- 1.Jet streams occur in the Northern Hemisphere only.
- 2.Only some cyclones develop an eye.
- 3.The temperature inside the eye of a cyclone is nearly 10°C lesser than that of the surroundings.
Which of the statements given above is/are correct ?
AnswerUPSC’s answer is (c).
Jet streams occur in both hemispheres, so statement 1 is wrong. Only some cyclones develop an eye: tropical cyclones have a calm eye, but mid-latitude (extratropical) cyclones do not, so statement 2 is right. The eye is warmer than its surroundings because air sinks and warms there, not about 10 degrees cooler, so statement 3 is wrong.
- 1. Jet streams occur in both hemispheres.
- 2. Tropical cyclones have an eye; mid-latitude cyclones do not.
- 3. The eye is warmer than its surroundings.
How you could have got this
- If you were sure statement 1 is not correct, (a) and (d) go: each of them includes 1.
What you needed to know: Jet streams occur in both hemispheres.
The red flag in statement 1 is “only”. In UPSC’s papers, statements with “only” were true 27% of the time (82 statements). A hint, not a rule.
- Then, if you were sure statement 3 is not correct, (b) goes: it includes 3.
What you needed to know: The eye is warmer than its surroundings.
Only (c) is left. You didn’t need statement 2.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Wrong: jet streams occur in both hemispheres.
- (b) Wrong: the eye is warmer, not cooler.
- (c) Right: statement 2 only.
- (d) Wrong: statements 1 and 3 are false.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2020, General Studies Paper I, Series A. The paper on upsc.gov.in.