2023 GS Paper I, all questions

UPSC Prelims 2023 · GS Paper I

Question 58: Science and Technology

Consider the following statements :

  1. 1.Ballistic missiles are jet-propelled at subsonic speeds throughout their flights, while cruise missiles are rocket-powered only in the initial phase of flight.
  2. 2.Agni-V is a medium-range supersonic cruise missile, while BrahMos is a solid-fuelled intercontinental ballistic missile.

Which of the statements given above is/are correct?

a1 only
b2 only
cBoth 1 and 2
dNeither 1 nor 2

AnswerUPSC’s answer is (d).

Both statements are wrong. A ballistic missile is rocket-powered in its initial boost phase and then follows a free-fall arc under gravity; a cruise missile is jet- or ramjet-propelled through its flight, so statement 1 reverses them. Agni-V is a nuclear-capable, solid-fuelled ballistic missile of intercontinental range, while BrahMos is a supersonic cruise missile, so statement 2 swaps them.

  • 1. Ballistic missiles use rocket boost; cruise missiles are jet-propelled.
  • 2. Agni-V is a ballistic missile; BrahMos is a supersonic cruise missile.

How you could have got this

  1. If you were sure statement 1 is not correct, (a) and (c) go: each of them includes 1.

    What you needed to know: Ballistic missiles use rocket boost; cruise missiles are jet-propelled.

    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.

  2. Then, if you were sure statement 2 is not correct, (b) goes: it includes 2.

    What you needed to know: Agni-V is a ballistic missile; BrahMos is a supersonic cruise missile.

Only (d) is left. This one needs every statement.

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) Statement 1 reverses the propulsion of ballistic and cruise missiles.
  • (b) Statement 2 swaps Agni-V and BrahMos.
  • (c) Both statements are wrong.
  • (d) Correct: neither statement is right.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2023, General Studies Paper I, Series A. The paper on upsc.gov.in.