Which of the following polymers involves cross-linkages.APolytheneBBakeliteCMelamineDVulcanized rubber

To determine which of the given polymers involves cross-linkages, let's analyze each option:

A) Polythene: Polythene, also known as polyethylene, is a polymer that does not involve cross-linkages. It is a linear polymer composed of repeating ethylene monomers.

B) Bakelite: Bakelite is a thermosetting polymer that involves cross-linkages. It is formed by the condensation polymerization of phenol and formaldehyde, resulting in a three-dimensional network structure.

C) Melamine: Melamine is a thermosetting polymer that involves cross-linkages. It is formed by the condensation polymerization of melamine and formaldehyde, resulting in a three-dimensional network structure.

D) Vulcanized rubber: Vulcanized rubber, also known as rubber with sulfur cross-links, involves cross-linkages. It is formed by the addition of sulfur to natural rubber, resulting in the formation of cross-links between polymer chains.

Based on the above analysis, the polymers that involve cross-linkages are Bakelite (B), Melamine (C), and Vulcanized rubber (D).