Class 12th

This is a multiple choice answer as classified in NCERT Exemplar

Option (A) and (B)

Explanation: The polymers that are not harmful to the environment are biodegradable polymers. PHBV (Poly beta-hydroxybutyrate co-beta-hydroxy valerate) is a biodegradable polymer. It undergoes bacterial degradation in the environment. PHBV is obtained by the polymerization of 3-hydroxybutyric acid and 3-hydroxypentanoic acid.

Nylon-2, Nylon-6 polymers are also biodegradable. It is obtained by the polymerization of glycine and aminocaproic acid.

This is a multiple choice answer as classified in NCERT Exemplar

Option (A) and (D)

Explanation: Condensation polymers are formed by the addition of more than one monomeric unit. Bakelite and Melamine formaldehyde resin are condensation polymers. Bakelite is a polymer formed from phenol and formaldehyde. Melamine formaldehyde resin is a polymer formed from melamine and formaldehyde.

This is a multiple choice answer as classified in NCERT Exemplar

Option (A) and (D)

Explanation: The formation of addition polymers is accomplished through the repeated addition of monomer molecules with double or triple bonds, such as polythene from ethene and polypropene from propene. Homopolymers are addition polymers formed by the polymerisation of a single monomeric species. 

This is a multiple choice answer as classified in NCERT Exemplar

Option (C) and (D)

Explanation: Fibers are thread-forming solids. They possess high tensile strength and high modulus. They have strong intermolecular forces of attraction like hydrogen bonding. Nylon and Terylene are used as fibers.

This is a multiple choice answer as classified in NCERT Exemplar

Option (A) and (D)

Explanation: Thermoplastic polymers are linear or slight branched-chain polymers. This type of polymer softens on heating and hardens on cooling. For example, Teflon and polystyrene are thermoplastic polymers.

So, options (A) and (D) are correct.

This is a multiple choice answer as classified in NCERT Exemplar

Option (A) and (C)

Explanation: Thermosetting polymers are cross linked polymers. These polymers on heating undergo cross linking in moulds. They become infusible on heating so cannot be reused again.

This is a multiple choice answer as classified in NCERT Exemplar

Option (B) and (C)

Explanation: Buna-S and neoprene are the polymers that needs at least one diene monomeric unit. Buna- S is a polymer formed from the polymerization of 1,3-butadiene and styrene. While, Neoprene is formed by the polymerisation of chloroprene.