Arrange the following substances in chronological order of their first synthesis in lab :
1. Black gold
2. Fullerene
3. Graphene
4. Kevlar
Select correct answer from the codes given below :
Codes :

Question

UnlockIAS · Accepted Answer

Correct — B, the order 4-2-3-1: Kevlar, then Fullerene, then Graphene, then Black gold. Kevlar (1965) is the oldest — the para-aramid fibre invented by Stephanie Kwolek at DuPont, five times stronger than steel by weight and the material of body armour, helmets and high-performance ropes. Fullerene came next: buckminsterfullerene, C60, the closed carbon cage shaped like a football, was discovered in 1985 by Harold Kroto, Robert Curl and Richard Smalley, who shared the 1996 Nobel Prize in Chemistry for it. Graphene — a single one-atom-thick sheet of carbon — was isolated in 2004 by Andre Geim and Konstantin Novoselov at the University of Manchester using the celebrated adhesive-tape method, and won the 2010 Nobel Prize in Physics. Black gold is the newest by a wide margin and the reason this question appeared in a December 2019 paper at all: it was reported in July 2019 by a team at the Tata Institute of Fundamental Research, Mumbai, led by Prof. Vivek Polshettiwar, and published in the Royal Society of Chemistry journal Chemical Science. So 1965 → 1985 → 2004 → 2019, that is 4, 2, 3, 1.

Why the other options are wrong — (a) This is simply the list in its printed order, and it inverts the two endpoints: it puts black gold (2019, the most recent of the four) first and Kevlar (1965, the oldest) last. Sequence questions frequently offer the untouched list as a decoy for candidates who run out of time.  (c) Gets graphene and black gold right at positions three and four, but swaps the first pair — it places fullerene (1985) before Kevlar (1965). Fixing Kevlar as the oldest of the four is the single check that kills this option.  (d) Starts correctly with Kevlar, then collapses: it puts black gold (2019) second, ahead of both fullerene (1985) and graphene (2004). Candidates fall for it when they treat 'black gold' as the old metaphor for petroleum or coal rather than as the 2019 nanomaterial.

Concept: Three of the four substances in this list are carbon materials and mark the milestones of materials science over half a century: an aramid polymer (Kevlar), a molecular carbon cage (fullerene) and a two-dimensional carbon sheet (graphene). The fourth, 'black gold', is not carbon at all — it is a gold nanomaterial, made of gold nanoparticles arranged as dendritic plasmonic colloidosomes, whose spacing was tuned so that the material absorbs almost the entire visible and near-infrared spectrum and therefore looks black instead of yellow. Its reported applications are solar-driven conversion of carbon dioxide to methane and solar seawater desalination.

State PCS 2019 Q93 — Science & Technology PYQ with Answer

State PCS 2019 Q93 — Science & Technology PYQ with Answer