Q.Distinguish between the terms homopolymer and copolymer and give an example of each.

Homopolymer: a polymer formed from only one type of monomer unit, so all repeat units in the chain are identical.

Example: Polythene, $-[-CH_2-CH_2-]_n-$, formed entirely from ethene ($CH_2=CH_2$) monomer units.

Copolymer: a polymer formed from two (or more) different types of monomer units, so the chain contains more than one kind of repeat unit, often arranged alternately or randomly.

Example: Buna-S, formed by copolymerisation of buta-1,3-diene ($CH_2=CH-CH=CH_2$) and styrene ($C_6H_5-CH=CH_2$).

Other examples: Nylon 6,6 (hexamethylenediamine + adipic acid) is also a copolymer, while Teflon ($-[-CF_2-CF_2-]_n-$, from tetrafluoroethene only) is another homopolymer.

Define each term by the number of distinct monomer types involved, then cite one clean addition-polymer example of each (polythene vs Buna-S) to avoid ambiguity.

• Calling Nylon 6 (from a single monomer, caprolactam) a copolymer just because it has two different functional groups in its repeat unit — it is a homopolymer since only one monomer type is used.
• Giving PVC (homopolymer of vinyl chloride) as a copolymer example by mistake.
• Not explaining what 'different type of monomer' means structurally.