UPSC Prelims 2023 Q58: Science & Technology – Defence Technology
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer: (d) Neither 1 nor 2
Explanation
Ballistic Missiles vs Cruise Missiles
| Statement | Claim | Verdict | Correct Facts |
|---|---|---|---|
| 1 | Ballistic missiles = jet-propelled at subsonic speeds throughout; cruise missiles = rocket-powered only initially | FALSE | This is completely reversed: Cruise missiles are jet-propelled (turbofan/turbojet engines) throughout their flight at low altitude. Ballistic missiles use rocket propulsion only in the initial boost phase — then follow a ballistic (unpowered) trajectory under gravity. |
| 2 | Agni-V = medium-range supersonic cruise missile; BrahMos = ICBM | FALSE | Completely reversed: Agni-V is a solid-fuelled Intercontinental Ballistic Missile (ICBM) with ~5,000+ km range. BrahMos is a supersonic cruise missile (Mach 2.8–3) developed jointly by India and Russia. |
Both statements are wrong → Neither 1 nor 2.
Answer: (d) Neither 1 nor 2.
Why each option is right or wrong
- (a) Incorrect. Statement 1 is false — it has the propulsion characteristics of ballistic and cruise missiles completely reversed.
- (b) Incorrect. Statement 2 is false — Agni-V is an ICBM, not a cruise missile; BrahMos is a cruise missile, not a ballistic missile.
- (c) Incorrect. 'Both 1 and 2' — both contain factual reversals of well-established missile classification facts.
- (d) CORRECT. Neither statement is correct — both reverse the true characteristics of ballistic and cruise missiles, and both misidentify Agni-V and BrahMos.
Key point
Cruise missile = sustained jet propulsion throughout flight (low altitude, subsonic/supersonic). Ballistic missile = rocket boost phase only, then unpowered trajectory. Agni-V = ICBM. BrahMos = supersonic cruise missile. Both statements have reversed information.
Remember
Cruise missiles use jet propulsion throughout their flight; ballistic missiles use rockets only in the initial boost phase. Agni-V is an ICBM (not a cruise missile); BrahMos is a supersonic cruise missile (not a ballistic missile). Both statements are false.
Common mistakes
- Accepting the propulsion descriptions without checking — cruise missiles cruise (sustained engine); ballistic missiles have rocket burn then coast on ballistic arc.
- Confusing Agni-V with a cruise missile — Agni-V is India's long-range ICBM (>5,000 km), tested for nuclear deterrence.
- Thinking BrahMos is a ballistic missile — BrahMos is India's fastest cruise missile, named from Brahmaputra + Moskva rivers (India-Russia joint venture).
Exam tip
Cruise = flies like an aircraft (jet engine throughout, low altitude). Ballistic = rocket launch → coasts like a thrown ball (only initial propulsion). BrahMos = supersonic cruise (Mach 2.8). Agni-V = ICBM (5000+ km). Both statements in question are reversed = Neither.
Sources
- DRDO — Agni-V and BrahMos Missile Systems
- NCERT Science — Defence Technology