Which one of the following polymers is not obtained by condensation polymerisation ?

The polymers made by addition polymerisation from two different monomers are termed as copolymers, e.g., Buna-S, Buna-N, etc.

Bakelite is a condensation polymer of formaldehyde and phenol . In practice, the phenol and formaldehyde are first polymerized to a small extent by using the proper choice of catalyst and temperature.

Nylon is also condensation polymer.