Answer: Extensive hydrogen bonding between amide groups in parallel chains.
- A Extensive hydrogen bonding between amide groups in parallel chains
- B A high density of covalent cross-links between adjacent chains
- C Weak van der Waals forces between the aromatic rings alone
- D Ionic interactions between charged groups along the backbone
Correct answer: A. Extensive hydrogen bonding between amide groups in parallel chains
Explanation: Kevlar chains are perfectly aligned and form extensive intermolecular hydrogen bonds between amide NH and C=O groups.
Addition polymerisation simply links monomers containing a double bond with nothing left over, while condensation polymerisation joins two different monomers through a reaction (often forming an ester or amide bond) that releases a small molecule like water at each step.
Concept context
Large molecules made of repeating monomer units. Covers addition and condensation polymerisation, natural and synthetic polymers (nylon, PVC, Bakelite, natural rubber), and their real-world industrial applications.