See image — Biomolecules Chemistry Question

💡 Solution & Explanation

Step 1 - Concept: Radical addition polymerization of a 1-alkene (alpha-olefin) proceeds by opening the C=C double bond. Each monomer unit adds to the growing chain via the terminal carbon, placing the substituent on every other carbon of the backbone. Step 2 - Analyze the polymer structure: The polymer shown has a long carbon backbone where every other carbon bears an n-butyl side chain (four carbons). The repeat unit is -CH2-CH(n-Bu)-, which corresponds to a monomer of the form CH2=CH-CH2CH2CH2CH3, i.e., hex-1-ene (1-hexene). The n-butyl group has four carbons, so the monomer is CH2=CH-(CH2)3CH3, which is hex-1-ene. Step 3 - Match to options: Option (c) shows a terminal alkene drawn with a clear double bond (two parallel lines) at the first carbon followed by a four-carbon chain, giving hex-1-ene (CH2=CHCH2CH2CH2CH3). This matches the repeat unit perfectly: radical polymerization opens the terminal double bond, the CH2 becomes part of the backbone, and the CH with the (CH2)3CH3 group also enters the backbone, producing the observed -[CH2-CH(n-Bu)]n- structure. Step 4 - Eliminate other options: (a) and (b) appear to show saturated chains or alkenes with fewer/different carbons without a clearly drawn terminal double bond matching the required substitution pattern. (d) shows a 1,1-disubstituted (vinylidene-type) alkene with a methyl branch at the terminal carbon, which would give a polymer with a gem-disubstituted repeat unit, not matching the monosubstituted backbone observed. Therefore, the correct answer is C.