JEE Main 2022 · 27 June · evening · Single correct · +4 / −1
Which is true about Buna-N?
- (a) It is a linear polymer of 1, 3-butadiene.
- (b) It is obtained by copolymerization of 1, 3-butadiene and styrene.
- (c) It is obtained by copolymerization of 1, 3-butadiene and acrylonitrile.
- (d) The suffix N in Buna-N stands for its natural occurrence.
Answer and solution
Answer (c) It is obtained by copolymerization of 1, 3-butadiene and acrylonitrile.
Solution
Chemistry ma’am · 3 steps
Decode the name: Bu for butadiene, na for sodium, and N for the nitrile in acrylonitrile.
- Read the name. In Buna, Bu stands for butadiene and na for sodium (Na), the catalyst used to start the polymerisation. The letter after the dash names the second monomer.
- Two monomers. Buna-N is a copolymer of 1,3-butadiene, CH₂=CH-CH=CH₂, and acrylonitrile, CH₂=CH-CN. The N comes from the nitrogen of the nitrile group, -C≡N.
Rubber Monomers Meaning of the letter Buna-N 1,3-butadiene + acrylonitrile N = nitrile Buna-S 1,3-butadiene + styrene S = styrene - So. Buna-N is made by copolymerising 1,3-butadiene with acrylonitrile, so the answer is (c). It is a synthetic rubber, valued for its resistance to oils and fuels.
The idea to keep. For Buna rubbers, read the name as a recipe: Bu is butadiene, na is the sodium catalyst, and the last letter names the partner monomer (S for styrene, N for nitrile).
Answer from the NTA final answer key. Solution by PrepWiser.