JEE Main 2021 · 24 February · morning · Single correct · +4 / −1
Match List I with List II .
Choose the correct answer from the options given below:
| List I (Monomer Unit) | List II (Polymer) |
|---|---|
| (a) Caprolactum | (i) Natural rubber |
| (b) 2-Chloro-1, 3-butadiene | (ii) Buna-N |
| (c) Isoprene | (iii) Nylon 6 |
| (d) Acrylonitrile | (iv) Neoprene |
- (a) (a) → (iv), (b) → (iii), (c) → (ii), (d) → (i)
- (b) (a) → (iii), (b) → (iv), (c) → (i), (d) → (ii)
- (c) (a) → (ii), (b) → (i), (c) → (iv), (d) → (iii)
- (d) (a) → (i), (b) → (ii), (c) → (iii), (d) → (iv)
Answer and solution
Answer (b) (a) → (iii), (b) → (iv), (c) → (i), (d) → (ii)
Solution
Chemistry ma’am · 4 steps
Read each monomer and ask what polymer it builds; caprolactam is the easy anchor at Nylon 6.
- Anchor the easy one. Caprolactam (spelt caprolactum in the list) is a cyclic amide with 6 carbon atoms. Heating it with a trace of water opens the ring and gives Nylon 6.
- Natural rubber. Natural rubber is cis-1,4-polyisoprene, so its monomer is isoprene, 2-methyl-1,3-butadiene.
- The two synthetic rubbers. Swap the methyl group of isoprene for a chlorine and you get chloroprene, 2-chloro-1,3-butadiene, which polymerises to neoprene. Buna-N is a copolymer of 1,3-butadiene and acrylonitrile, CH₂=CH-CN; the N stands for the nitrile group.
Monomer (List I) Polymer (List II) (a) Caprolactam (iii) Nylon 6 (b) 2-Chloro-1,3-butadiene (iv) Neoprene (c) Isoprene (i) Natural rubber (d) Acrylonitrile (ii) Buna-N - So. The match is (a) → (iii), (b) → (iv), (c) → (i), (d) → (ii), which is option (b).
The idea to keep. Learn rubbers as variations on butadiene: a methyl at C-2 gives isoprene (natural rubber), a chlorine gives chloroprene (neoprene). Buna-S has styrene, Buna-N has acrylonitrile.
Answer from the NTA final answer key. Solution by PrepWiser.