UPSC Prelims 2025 Q46: Science & Technology – Defence Technology
- (a) These are alternatives to hydrofluorocarbon refrigerants
- (b) These are explosives in military weapons
- (c) These are high - energy fuels for cruise missiles
- (d) These are fuels for rocket propulsion
Answer: (b) These are explosives in military weapons
Explanation
Chemical Compounds - Identification:
| Compound | Full Name | Type | Military Use |
|---|---|---|---|
| CL-20 (HNIW) | Hexanitrohexaazaisowurtzitane | High explosive | Most energetically dense conventional explosive - used in advanced warheads |
| HMX | High Melting Explosive (cyclotetramethylene-tetranitramine) | High explosive | Nuclear weapon trigger charges, rocket propellant boosters, shaped charges |
| LLM-105 (DNAFO) | 2,6-Diamino-3,5-dinitropyrazine-1-oxide | Insensitive munition explosive | Safer explosive reducing accidental detonation risk in weapons |
All three are military-grade high-energy explosives used in weapons systems.
None are refrigerant alternatives, standalone rocket fuels, or cruise missile fuels.
Explosive power ranking: CL-20 > HMX > RDX > TNT.
Answer: (b) These are explosives in military weapons.
Why each option is right or wrong
- (a) Incorrect. None of these are HFC refrigerant alternatives. HFC replacements are HFOs like HFO-1234yf — completely different chemistry and purpose.
- (b) CORRECT. CL-20, HMX, and LLM-105 are all military-grade explosives. HMX triggers nuclear weapon compression; CL-20 is among the most powerful conventional explosives; LLM-105 is an insensitive explosive for safer munitions handling.
- (c) Incorrect. These are solid explosives, not high-energy liquid fuels for cruise missile propulsion. Cruise missiles use turbofan engines with jet fuel.
- (d) Incorrect. These are explosives used in weapons, not liquid rocket propellants. Rocket fuels (RP-1, liquid H₂, UDMH) are entirely different chemical compounds.
Key point
CL-20 + HMX + LLM-105 = Military-grade explosives. Power order: CL-20 > HMX > RDX > TNT. LLM-105 = insensitive (safer to handle).
Remember
CL-20, HMX, LLM-105 = military explosives (not fuels, not refrigerants). CL-20 > HMX > RDX > TNT in power.
Common mistakes
- Confusing explosives with fuels. Explosives detonate (rapid decomposition, shock wave). Fuels combust with oxygen in a controlled reaction. Fundamentally different physics.
- Not knowing HMX is used in nuclear weapon trigger charges — it provides the precise high-energy shockwave to compress fissile material to criticality.
- Confusing CL-20 (explosive) with HFC alternatives (refrigerant chemicals). Completely different compound classes and applications.
Exam tip
Military explosive ranking: CL-20 > HMX > RDX > TNT (most to least powerful). LLM-105 = insensitive = does not detonate easily = safer munitions. DRDO researches these at HEMRL (High Energy Materials Research Laboratory), Pune.
Sources
- DRDO — High Energy Materials Research Laboratory (HEMRL), Pune
- Jane's Defence Technology — Explosive Compounds
- NCERT Class XII — Chemistry (Energetic Materials)