UPSC Prelims 2025 · GS Paper I

Question 46: Science and Technology

What is the common characteristic of the chemical substances generally known as CL-20, HMX and LLM-105, which are sometimes talked about in media?

aThese are alternatives to hydrofluorocarbon refrigerants

bThese are explosives in military weapons

cThese are high-energy fuels for cruise missiles

dThese are fuels for rocket propulsion

AnswerThe answer is (b).

CL-20, HMX and LLM-105 are high-energy explosive compounds. HMX is a widely used military explosive, CL-20 is among the most powerful known conventional explosives, and LLM-105 is a newer insensitive high explosive. They go into warheads, munitions and some propellant mixtures. They are not refrigerants, and they are not the fuels burned in a cruise missile engine or a rocket engine. Remember: all three are military explosives.

Why each option is right or wrong

(a) Wrong: alternatives to hydrofluorocarbons are refrigerants such as natural gases, not explosives.
(b) Right: all three are high-energy explosives used in military weapons.
(c) Wrong: cruise missile engines burn liquid fuels, while these compounds are explosives.
(d) Wrong: rocket fuels are propellants; these are explosives.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2025, General Studies Paper I, Series A. The paper on upsc.gov.in.