Which among the following is not a natural polymer?
(a) Wool
(b) Silk
(c) Rubber
(d) PVC

Hint: A polymer is a compound which is made by a combination of many subunits or monomers. It is therefore also known as a macromolecule. Any polymer which is derived from nature is a natural polymer, whereas, any polymer which is man-made is known as synthetic polymer.

Complete step by step answer:
Polymers are widely distinguished as natural and synthetic polymers according to the source from which it is derived.
The polymers occurring naturally, and derived from natural resources such as plants and animals are called natural polymers.
The polymers which are not derived from the natured but manufactured by man are known as synthetic polymers.
Let us look at the given options –
1) Wool:
It is a textile polymer/ fiber, which is obtained from animals such as sheep.
Therefore, it is a natural polymer.

2) Silk:
It is a natural protein fiber, which is obtained from larvae of certain worms, especially mulberry silkworm.
Therefore, it is a natural polymer.

3) Rubber:
Natural rubber is a polymer of isoprene, which is derived from rubber trees.
It is a natural polymer.

4) PVC:
PVC stands for polyvinyl chloride.
It is made by the polymerization reaction of monomer vinyl chloride.
It is the third most widely produced synthetic fiber.

Therefore, the answer is – option (d) – PVC is not a natural polymer.

Additional Information: Biodegradable polymers are known as biopolymers.

Note: Other than natural and synthetic polymers, there is another category of polymers known as semi-synthetic polymers. These polymers are obtained from naturally occurring polymers, which are further treated for chemical modifications. It includes cellulose nitrate, cellulose acetate, etc.