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?

Updated 10 Apr 2026 · From UPSC Prelims GS Paper I 2025, Q6

Contents7
UPSC Prelims GS2025Science and Technology
  1. AThese are alternatives to hydro-fluorocarbon refrigerants
  2. BThese are explosives in military weapons
  3. CThese are high-energy fuels for cruise missiles
  4. DThese are fuels for rocket propulsion
Show answer

Answer: (B) These are explosives in military weapons

This is a straightforward factual question.

CL-20, HMX, and LLM-105 are all high-energy explosive compounds used primarily in military applications.

  • CL-20 (also called HNIW) — One of the most powerful non-nuclear explosives known. It has very high energy density and is used in advanced munitions.

  • HMX (High Melting Explosive / Her Majesty's Explosive) — A powerful and relatively insensitive military explosive used in plastic explosives, rocket propellants, and shaped charges.

  • LLM-105 — A newer explosive developed at Lawrence Livermore National Laboratory. It is notable for being both powerful and relatively insensitive to accidental detonation, making it safer to handle.

They are NOT refrigerant alternatives (those would be HFOs or natural refrigerants), NOT fuels for cruise missiles, and NOT rocket propulsion fuels (those would be solid/liquid propellants like hydrazine).

The common thread is that they are all explosives used in military weapons.

Answer is (b).

Why this was asked

CL-20, HMX and LLM-105 are high-energy explosive compounds used in advanced military weapons and munitions.

These explosives have been in defense news due to ongoing military modernization programs and development of next-generation munitions systems.

UPSC is testing whether students can distinguish between explosives and propellants - both are military chemicals but serve different functions.

High-Energy Military Explosives

Science And Technology CL-20 HMX LLM-105 explosives military weapons

High-Energy Military Explosives: CL-20, HMX & LLM-105

Must know

CL-20, HMX, and LLM-105 are all high-energy explosive compounds used in military weapons

CL-20 is one of the most powerful non-nuclear explosives with very high energy density

Good to know

HMX is used in plastic explosives, rocket propellants, and shaped charges

LLM-105 is safer to handle while maintaining high explosive power

What Are They

These are chemical explosive compounds developed for advanced military applications. Unlike conventional explosives, they offer extremely high energy density while maintaining stability during storage and transport.

Key Military Explosives

Explosive

Full Name/Origin

Key Characteristic

Primary Use

CL-20

HNIW (Hexanitrohexaazaisowurtzitane)

Most powerful non-nuclear explosive

Advanced munitions

HMX

High Melting Explosive / Her Majesty's Explosive

Powerful and relatively insensitive

Plastic explosives, shaped charges

LLM-105

Lawrence Livermore Laboratory development

High power + safety (insensitive)

Next-generation military applications

Technical Properties

Energy density — These explosives release more energy per unit mass than conventional explosives like TNT

Insensitive munitions — Designed to resist accidental detonation from heat, shock, or friction

Chemical stability — Can be stored for long periods without degradation

Military-grade — Used in advanced weapons systems requiring maximum explosive power

Exam traps

Not refrigerant alternatives — Those are HFOs or natural refrigerants like ammonia

Not cruise missile fuels — Cruise missiles use jet fuel or other hydrocarbon fuels

Not rocket propellants — Rockets use liquid/solid propellants like hydrazine or HTPB

All three are explosives, not fuels — they detonate rather than burn steadily

Military vs Civilian Chemical Applications

Science And Technology refrigerants fuels propulsion

Distinguishing Military & Civilian Chemical Applications

Must know

Military explosives detonate rapidly to cause damage, unlike fuels that burn steadily

Refrigerants are cooling agents, not explosive compounds

Good to know

Propellant fuels provide thrust through controlled combustion

Chemical Applications Comparison

Application

Purpose

Chemical Action

Examples

Military Explosives

Cause damage/destruction

Rapid detonation

CL-20, HMX, LLM-105, TNT

Refrigerants

Heat transfer/cooling

Phase change absorption

HFCs, HFOs, Ammonia

Cruise Missile Fuels

Sustained flight power

Controlled combustion

Jet fuel, Hydrocarbons

Rocket Propellants

Generate thrust

Rapid combustion

Hydrazine, HTPB, Liquid oxygen

Key Distinctions

Explosives — Instantaneous energy release for destructive effect

Fuels — Sustained energy release for propulsion or power

Refrigerants — Heat absorption/release for cooling systems

Propellants — Controlled combustion for directed thrust