Free Polymers MCQs with Answers

11. Recycling thermoplastics is possible but recycling thermosetting plastics is not, because thermosetting plastics

• A. are always coloured
• B. are made from natural materials
• C. cannot be melted and reshaped once their cross links have formed
• D. dissolve in water

Explanation: The permanent covalent network of a thermoset means heating it decomposes the material rather than softening it, so it can only be ground into filler or burnt for energy recovery. A thermoplastic has independent chains held by weak forces, so it can be melted and re-formed many times. This is why sorting plastic waste by type is the first step in any recycling scheme.

12. Which polymer is used to make drinking bottles and is widely recycled?

• A. Bakelite
• B. Polyethylene terephthalate
• C. Urea formaldehyde resin
• D. Melamine resin

Explanation: Polyethylene terephthalate is a thermoplastic polyester that is clear, tough and impermeable to carbon dioxide, and because it melts without decomposing it can be recycled into fibre or new bottles. The other three are thermosetting resins used for electrical fittings, adhesives and tableware and cannot be remelted. Recycling codes on packaging identify the polymer for exactly this reason.

13. The general requirement for a monomer to undergo addition polymerisation is that it must contain

• A. at least two different functional groups
• B. a benzene ring
• C. a hydroxyl group
• D. a carbon to carbon double bond

Explanation: The pi bond opens so that each unit can bond to the next with nothing eliminated, which is why ethene, propene, chloroethene and styrene all polymerise this way. Two different functional groups are what condensation polymerisation needs, as in the diamine and diacid of nylon. Checking for the double bond is the quickest way to classify an unfamiliar polymerisation.

14. Poly vinyl chloride (PVC) is the type of:

• A. Homopolymer
• B. Thermosetting polymer
• C. Thermoplastic polymer
• D. Copolymer

Explanation: This is the option marked correct in the official UHS answer key. PVC softens on heating and can be remoulded repeatedly because its chains are separate and held only by weak intermolecular forces, which is what thermoplastic means and is why it is recyclable. It is also a homopolymer, since it is built from one monomer, chloroethene, so option (a) is true as well and this question turns on which classification the examiner intended.