Among the following polymers, which one is the copolymer?

Glyptal

Homopolymers consist of single species of repeating units whereas copolymers consist of two or more types of repeating units. Polypropylene, Polystyrene, and Polyvinyl chloride: Homopolymer Glyptal: Copolymer

Glyptal is polyesters formed by the condensation of organic acids having two acid functional groups such as phthalic acid, maleic acids, etc, and alcohols with two or more hydroxyl groups. They are also called alkyd resins.

Malonic acid (COOH−CH₂−COOH) and ethylene glycol given in option (A) do not form polyester. Though malonic acid is a saturated dibasic acid, it is very unstable and heating gives acetic acid.

The simplest glyptal is formed by the polymerization of dibasic phthalic acid and dihydric alcohol, i.e., ethylene glycol with the removal of water as a byproduct. The polymer thus formed is called poly (ethylene phthalate).