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:

Work out the dates first. Kevlar (4) was developed by Stephanie Kwolek at DuPont in 1965, patented in 1966 and commercialised around 1971, so it is the oldest on the list. Fullerene (2), the C60 buckyball, was identified in 1985 by Kroto, Curl and Smalley, who won the 1996 Nobel Prize. Bulk production came later, in 1990.

Graphene (3) was isolated as a single atomic layer in 2004 by Geim and Novoselov at Manchester, using the scotch-tape method. They won the 2010 Nobel Prize. Black gold (1) is nanostructured or nanoparticle gold, a material that came out of 2000s nanoscience, so it is the most recent. Option B (4 2 3 1) follows this order.

• Option A puts black gold first, which is wrong because it is the newest of the four.
• Option C places fullerene before Kevlar, but Kevlar predates the 1985 fullerene identification.
• Option D places Kevlar after black gold and graphene, which is wrong on both counts.

Core concept: chronology of materials science milestones. This links to Science and Technology, especially nanotechnology, and to Mains papers on emerging materials and their applications.

Trap: aspirants often assume graphene is older because it is famous. Graphene's Nobel-winning isolation came in 2004, after fullerene's 1985 discovery.