Ten original SPM-style multiple-choice questions and three structured questions with full model answers for the Form 5 Polymers chapter, covering monomer and polymer identification, addition versus condensation, vulcanisation, and the uses and environmental issues of polymers.
Attempt each question before reading the answer. These are original questions written in SPM style on the Polymers content standards, we never reproduce past-year papers. The multiple-choice section mirrors Paper 1 is an objective (multiple-choice) paper; the structured section trains the longer written answers.
Multiple-choice questions
1. Which statement best defines a polymer? A. A small molecule with a double bond B. A large molecule made of many repeating units C. A mixture of two liquids D. An element with a giant structure
Answer: B. A polymer is a macromolecule built from many small repeating units (monomers).
2. Which of the following is a natural polymer? A. Polythene B. PVC C. Natural rubber D. Nylon
Answer: C. Natural rubber comes from the latex of the rubber tree; the others are synthetic.
3. What is the monomer of poly(chloroethene), PVC? A. CH₂=CH₂ B. CH₂=CHCl C. CH₂–CHCl D. CHCl=CHCl
Answer: B. The monomer is chloroethene, CH₂=CHCl, an unsaturated molecule with a C=C double bond.
4. Ethene forms polythene. Which is the repeating unit of polythene? A. –CH₂=CH₂– B. –CH₂–CH₂– C. CH₂=CH₂ D. –CHCl–CH₂–
Answer: B. In the addition polymer the double bond has opened, leaving –CH₂–CH₂– with single bonds.
5. A monomer has one carbon–carbon double bond and no other functional group. Which type of polymerisation will it undergo? A. Condensation B. Neutralisation C. Addition D. Oxidation
Answer: C. An unsaturated monomer joins by addition polymerisation with no by-product.
6. Which pair of monomers undergoes condensation polymerisation? A. Ethene and propene B. A diamine and a dicarboxylic acid C. Chloroethene and ethene D. Two molecules of phenylethene
Answer: B. Monomers with two functional groups (here –NH₂ and –COOH) join by condensation, releasing water.
7. Which small molecule is usually released when nylon is formed? A. Carbon dioxide B. Hydrogen C. Oxygen D. Water
Answer: D. Condensation polymerisation eliminates a small molecule, here water, each time a bond forms.
8. Which substance is used to vulcanise rubber? A. Chlorine B. Sulfur C. Ammonia D. Ethanoic acid
Answer: B. Rubber is vulcanised by heating it with sulfur, which forms cross-links between the chains.
9. Compared with unvulcanised rubber, vulcanised rubber is A. softer and weaker B. harder and more elastic C. more easily melted D. more sticky
Answer: B. Sulfur cross-links tie the chains together, making the rubber harder, stronger and more elastic.
10. Which is the main environmental problem with most synthetic polymers? A. They dissolve in water B. They are non-biodegradable C. They rust quickly D. They evaporate easily
Answer: B. Most synthetic polymers cannot be broken down by microorganisms, so waste accumulates for a long time.
Structured questions
Structured question 1, Identifying monomers and type of polymerisation
A polymer P has the repeating unit –CH₂–CH₂– written inside brackets with subscript n. A second polymer Q is a polyester made from a diol and a dicarboxylic acid.
(a) Name the monomer of polymer P and its formula. (2 marks) (b) State the type of polymerisation that forms P. (1 mark) (c) State the type of polymerisation that forms Q and name the small molecule released. (2 marks)
Model answer. (a) The monomer is ethene, CH₂=CH₂. Restore the double bond between the two carbons of one repeating unit. (b) Addition polymerisation, because the monomer is unsaturated and no by-product is released. (c) Condensation polymerisation; the small molecule released is water, eliminated each time an ester link forms between the –OH and –COOH groups.
Structured question 2, Natural rubber and vulcanisation
Latex is a colloid of rubber particles dispersed in water.
(a) Explain why latex coagulates when an acid is added. (2 marks) (b) State how latex can be prevented from coagulating during transport. (1 mark) (c) Describe how vulcanisation changes the structure of rubber, and state two property changes that result. (3 marks)
Model answer. (a) Each rubber particle is wrapped in a membrane carrying a negative charge, so the particles repel one another. Adding an acid neutralises the charge, so the particles collide, join and the latex coagulates. (b) Add a little alkali such as ammonia solution, which keeps the negative charge and stops the particles clumping. (c) Vulcanisation heats rubber with sulfur, and sulfur atoms form cross-links (sulfur bridges) between the poly(isoprene) chains at the double bonds. The chains can no longer slide far apart. As a result the rubber becomes harder and more elastic (also stronger, with a higher elasticity limit and better resistance to heat).
Structured question 3, Uses and environmental issues
Synthetic polymers such as polythene and PVC have replaced many traditional materials in packaging.
(a) State two properties that make synthetic polymers useful for packaging. (2 marks) (b) Explain one environmental problem caused by the disposal of synthetic polymers. (2 marks) (c) Suggest two ways to reduce this environmental problem. (2 marks)
Model answer. (a) They are light and waterproof (also cheap, strong and easily moulded), any two suitable properties. (b) Most synthetic polymers are non-biodegradable, so microorganisms cannot break them down; the waste accumulates on land and in the sea for a very long time. (Open burning of PVC also releases hydrogen chloride, an acidic corrosive gas.) (c) Reduce, reuse and recycle plastics; develop and use biodegradable or photodegradable plastics; and avoid open burning by disposing of plastics properly. Any two.
Marking yourself
Give yourself the mark only when your answer contains the exact point the model answer names, the restored double bond, the released molecule, the sulfur cross-links, or the balanced environmental argument. Marking loosely, and giving yourself credit for an answer that is roughly right, is the fastest way to walk into the exam believing you know a topic you have not yet nailed. A one-to-one teacher can check your structured answers line by line against these mark points, which is where most of the SPM Chemistry marks in this chapter are won or lost. When every question here feels routine, revisit the two that you found hardest, then move on to the worked examples and common mistakes for the chapter to close any remaining gaps before the real papers.
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