Concept:Polystyrene is an aromatic addition polymer formed by the chain-growth polymerization of styrene (phenylethene).
Formula / Reaction:$$n\,\text{C}_6\text{H}_5-\text{CH}=\text{CH}_2 \xrightarrow{\text{Initiator}} -[\text{CH}(\text{C}_6\text{H}_5)-\text{CH}_2]_n-$$
Solution:- The repeating unit of polystyrene contains a saturated carbon backbone with a pendant phenyl (\(-\text{C}_6\text{H}_5\)) ring attached to alternating carbon atoms, as depicted in Structure A.
Why other options are incorrect:- Structure B: Represents polyvinyl chloride (PVC) with a pendant chloro (\(-\text{Cl}\)) group.
- Structure C: Represents polyethylene (low- or high-density polyethene).
- Structure D: Represents polypropylene with a pendant methyl (\(-\text{CH}_3\)) group.
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