What is the name of monomer used in the formation of a polymer ?

What is the name of monomer used in the formation of a polymer
?
  1. Isoprene
  2. Tetrafluoroethylene
  3. Acrylonitrile
  4. Caprolactum

Solution

The repeating unit $\text{–CH}_2\text{–C(CH}_3)\text{=CH–CH}_2\text{–}$ indicates 1,4-addition polymerization of a conjugated diene.

Reversing the polymerization by breaking the terminal single bonds and reforming the conjugated system yields the monomer $\text{CH}_2\text{=C(CH}_3)\text{–CH=CH}_2$, known as isoprene.

Comparing with options: tetrafluoroethylene ($\text{CF}_2\text{=CF}_2$) forms Teflon; acrylonitrile ($\text{CH}_2\text{=CH–CN}$) forms polyacrylonitrile; caprolactam undergoes ring-opening polymerization to form Nylon-6. Only isoprene corresponds to the given structure.

Final answer: $\boxed{A}$

Asked in: MHT CET 2025 (05 May Shift 2)

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