Concept:Buna-S is a synthetic rubber, and all rubbers belong to the class of polymers known as elastomers.
Explanation:Buna-S is a copolymer prepared by the polymerisation of 1,3-butadiene (
CH2​=CH−CH=CH2​) and styrene (
C6​H5​−CH=CH2​).
The name "Buna" comes from
Bu (butadiene) and
Na (sodium, used as a catalyst), while
S stands for styrene.
It is a synthetic rubber that exhibits rubber-like elasticity, meaning it can be stretched repeatedly and returns to its original shape when the stress is removed.
Polymers that show this elastic behaviour are classified as elastomers.
Therefore, Buna-S, being a synthetic rubber with high elasticity, is correctly categorised as an elastomer.
It is widely used in the manufacture of tyres, footwear, hoses, and other rubber products.
Fibres are strong, crystalline polymers, thermoplastics soften on heating, and thermosetting polymers become infusible on heating — none of these apply to Buna-S.
Answer:Option A: elastomer