High molecular mass macromolecules are called polymers which consist of repeating structural units derived from corresponding monomers. These polymers can be classified in a number of ways, such as based on their source, method of preparation intermolecular forces of attraction etc.
Natural rubber is a polymer of cis-1, 4-isoprene and can be made tough with vulcanisation process. Polymers are useful in manufacturing of various materials such as toys, fibres, pipes, television cabinets etc.
In view of potential environmental hazards of waste disposal certain biodegradable polymers are synthesised such as PHBV.
Based on the paragraph given above answer the questions
Which among the following statement is Not true for copolymer Buna-N?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → It is used in the manufacture of unbreakable crockery
Buna-N is a synthetic rubber made by copolymerising 1,3-butadiene and acrylonitrile in the presence of a peroxide catalyst:
n \( \ce{CH2=CH-CH=CH2} \) + n \( \ce{CH2=CH-CN} \) → –[CH2–CH=CH–CH2–CH2–CH(CN)]n–
It is resistant to petrol, lubricating oil and organic solvents and is used for oil seals and tank linings.
Option (1) It contains cyano group — True for Buna-N. The acrylonitrile units carry –CN groups.
Option (2) It is used in the manufacture of unbreakable crockery — Not true for Buna-N. Unbreakable crockery is made from melamine–formaldehyde polymer; Buna-N is used for oil seals and tank linings.
Option (3) It is a copolymer of 1, 3-Butadiene and acrylonitrile — True for Buna-N. These are its two monomers.
Option (4) It is an example of synthetic rubber — True for Buna-N. Buna-N and neoprene are synthetic rubbers.
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Buna-N
