Q.Explain the terms polymer and monomer.

Polymers are very large molecules (macromolecules) built by covalently linking together thousands of small, repeating units called monomers. The number of repeat units in a chain is called its degree of polymerisation.

• Monomer: the small reactive molecule that repeats to form the chain
• Functionality: the number of bonding sites on a monomer; it needs functionality ≥ 2 to polymerise — bifunctional monomers give linear chains, higher functionality gives branched or cross-linked networks
• Polymerisation: $n\,\text{CH}_2{=}\text{CH}_2 \rightarrow +(\text{CH}_2\text{-CH}_2)_n+$