What is/are the full form(s) of HMX?

1. High Melting Explosive

2. High-Density Monoatomic Xenon

3. Hedge Monetizing Xenocurrency

4. Her Majesty’s Explosive Select the correct answer using the codes given below.

Question

UnlockIAS · Accepted Answer

Correct — D, 1 and 4. HMX, also called octogen, is a nitroamine high explosive with the formula C4H8N8O8: an eight-membered ring of alternating carbon and nitrogen atoms carrying a nitro group on every nitrogen. Its name has never been formally settled. The standard reference work on the subject — Paul W. Cooper, Explosives Engineering (New York: Wiley-VCH, 1996) — records the letters as having been variously expanded to High Melting Explosive, High-velocity Military Explosive, High-Molecular-weight RDX and Her Majesty's Explosive. Two of those four are on this page, as items 1 and 4, and both are genuine. 'High Melting' is not a guess: HMX melts at 276–286 °C where its close relative RDX melts at 205.5 °C, and since the two compounds are made by the same Bachmann nitration of hexamine and separated only by reaction conditions, the higher-melting product needed a name that distinguished it. 'Her Majesty's Explosive' reflects the British wartime naming habit that also left RDX with two competing expansions of its own — Research Department Explosive and Royal Demolition Explosive. Items 2 and 3 are where the paper does its filtering: 'High-Density Monoatomic Xenon' names no explosive (xenon is an inert monatomic gas used in lamps, ion thrusters and anaesthesia) and 'Hedge Monetizing Xeno-currency' is not chemistry at all. The stem's own plural, 'full form(s)', is the setter telling you that more than one item is meant to survive. This is a derived answer rather than a published one, and it is the one place on this question where honesty matters: see the reasoning below for why option (c) is a live rival rather than a dead one.

Why the other options are wrong — (a) Item 1 is right, but item 2 is invented. 'High-Density Monoatomic Xenon' strings together real physics words — xenon is genuinely monatomic and genuinely dense for a gas — into a compound that does not exist and names no energetic material. Xenon is a chemically inert noble gas used in high-intensity lamps, in ion thrusters and as an anaesthetic; nothing about it detonates. Choosing this option means accepting a scientific-sounding phrase without first asking whether it could name an explosive at all.  (b) The only option that contains neither genuine expansion, so it is wrong twice over. It pairs the fabricated 'High-Density Monoatomic Xenon' with 'Hedge Monetizing Xeno-currency', a finance-flavoured string with no chemical meaning whatever. A candidate lands here only by having no anchor on HMX at all and being drawn to the two most exotic-sounding items on the page — which is precisely what the setter built them for.  (c) The serious rival, and the reason this question is not open-and-shut. 'High Melting Explosive' is the single expansion that most Indian defence writing and general-knowledge compilations give, so an examiner working from one such source could have intended (c). What tips the page towards (d) is that 'Her Majesty's Explosive' is equally documented in the standard explosives literature, not a distractor invented for this paper, and that the stem deliberately asks for the 'full form(s)' in the plural — a construction with no purpose if exactly one item were correct.

Concept: HMX belongs to the nitroamines (nitramines), the family of secondary high explosives built around nitrogen–nitrogen nitro linkages, alongside RDX and tetryl. An energetic material of this kind carries its fuel and its oxidiser inside one molecule: the nitro groups supply the oxygen that burns the carbon and hydrogen skeleton, which is why detonation does not need air and propagates as a shock wave rather than a flame. Performance is compared on three numbers. Detonation velocity is the speed at which that shock front travels — about 6,900 m/s for TNT, 8,750 m/s for RDX and 9,100 m/s for HMX. Relative effectiveness takes TNT as 1.00, putting RDX at 1.60 and HMX at 1.70. Sensitivity decides whether a compound can be handled: HMX is rated low for both shock and friction sensitivity, which is what makes it a secondary explosive needing a detonator, and not a primary one like mercury fulminate. Because it is expensive and hard to make, HMX is reserved for jobs where the extra energy per unit volume is worth it.

State PCS 2023 Q12 — Science & Technology PYQ with Answer

State PCS 2023 Q12 — Science & Technology PYQ with Answer