References only, not question text. Open Official paper ↗ where Cambridge publishes the paper,
or see the official Cambridge past-papers page; for other papers, ask your
school. “Paper 42” means Paper 4, variant 2.
Practice questions
Original questions written by HomiLabs in the style of the exam, with answers and mark schemes. They are not
Cambridge past paper questions and have not been reviewed by Cambridge. Try each one before opening the answer.
Q1Addition polymers · Core · Paper 2 style · 5 marks
Water pipes and crates sold in Pakistani markets are often made from poly(propene) and poly(chloroethene).
(a)Write the repeat unit of poly(propene). Use the form –CH₂–CHX– with X identified.[1]
(b)Give the structural formula and name of the monomer used to make poly(chloroethene), PVC.[2]
(c)State the type of polymerisation and why no other product forms.[2]
Show answer
(a) –CH₂–CH(CH₃)–
B1 continuation bonds shown at both ends.
(b) CH₂=CHCl, chloroethene
B1 formula; B1 name.
(c) Addition polymerisation; the C=C π bonds open and monomers join with no atoms lost, so the polymer is the only product.
B1 addition; B1 explanation.
Q2Addition polymers · Core · Paper 1 style · 1 mark
(a)[1]
Show answer
(a) C CH₂=CCl₂
Both Cl atoms are on the same carbon of the repeat unit, so the monomer is 1,1-dichloroethene. B would give –CHCl–CHCl–.
Q3Addition polymers · Core · Paper 2 style · 4 marks
(a)Give the structural formula of the monomer and the repeat unit of PTFE, poly(tetrafluoroethene).[2]
(b)Explain why PTFE is very unreactive, making it suitable for non-stick cooking pans.[2]
Show answer
(a) Monomer CF₂=CF₂; repeat unit –CF₂–CF₂–
B1 each.
(b) The C–F bonds are very strong (high bond energy) and the polymer is saturated (no C=C), so it resists attack by most chemicals.
B1 strong C–F bonds; B1 saturated/non-polar overall, no reactive sites.
Q4Addition polymers · Core · Paper 2 style · 4 marks
Expanded polystyrene is used to pack electronic goods and to make disposable food boxes.
(a)Give the name and structural formula of the monomer of polystyrene.[2]
(b)Give the repeat unit of polystyrene.[1]
(c)Explain why poly(alkene)s such as polystyrene are chemically unreactive.[1]
Show answer
(a) phenylethene (styrene), C₆H₅CH=CH₂
B1 name; B1 formula.
(b) –CH₂–CH(C₆H₅)–
B1.
(c) They are saturated (contain no C=C in the chain) and have strong non-polar C–C and C–H bonds.
B1.
Q5Addition polymers · Standard · Paper 2 style · 3 marks
(a)A molecule of poly(ethene) has Mr = 280 000. Calculate the number of monomer units in the molecule. [Mr of C₂H₄ = 28.0][1]
(b)A chain of poly(chloroethene) contains 2000 monomer units. Calculate its Mr. [Mr of C₂H₃Cl = 62.5][1]
(c)Explain why a sample of poly(ethene) is described by an average Mr rather than a single value.[1]
Show answer
(a) 10000
B1 280 000/28.0.
(b) 125 000
B1 2000 × 62.5.
(c) Chains grow and stop at random, so the polymer contains chains of different lengths.
B1.
Q6Addition polymers · Standard · Paper 2 style · 5 marks
A city council plans to reduce waste from thin plastic shopping bags made of poly(ethene) and from PVC pipes.
(a)Explain why poly(alkene)s cause problems in landfill sites.[2]
(b)Explain why burning PVC waste is particularly harmful.[2]
(c)Suggest one advantage of recycling over incineration.[1]
Show answer
(a) They are non-biodegradable because they are saturated/non-polar with strong C–C and C–H bonds; microorganisms cannot break them down, so they persist for many years.
B1 non-biodegradable; B1 reason (inert, no polar bonds for enzymes to attack).
(b) Combustion releases toxic and acidic hydrogen chloride gas (and possibly toxic chlorinated compounds); HCl causes acid rain/respiratory damage.
B1 HCl produced; B1 harmful effect.
(c) Saves crude oil (raw material) and energy; no toxic gases released.
B1.
Q7Addition polymers · Standard · Paper 1 style · 1 mark
(a)Part of a polymer chain is shown: –CH₂–CH(CN)–CH₂–CH(CN)–CH₂–CH(CN)–What is the monomer?[1]
Show answer
(a) A CH₂=CHCN
The repeat unit is –CH₂–CH(CN)–, from propenenitrile CH₂=CHCN. B has no C=C so cannot undergo addition polymerisation.
Q8Addition polymers · Standard · Paper 4 style · 4 marks
A section of a copolymer used for flexible food packaging is: –CH₂–CH₂–CH₂–CH(CH₃)–CH₂–CH₂–CH₂–CH(CH₃)–
(a)Identify the two monomers used to make this polymer.[2]
(b)State the type of polymerisation and give the empirical formula of the polymer if the monomers are present in equal numbers.[2]
Show answer
(a) ethene, CH₂=CH₂, and propene, CH₂=CHCH₃
B1 each.
(b) Addition; CH₂
B1 addition; B1 C₅H₁₀ per pair → CH₂.
Q9Addition polymers · Standard · Paper 2 style · 5 marks
(a)Draw (as a text formula) the repeat unit of the polymer formed from but-2-ene, CH₃CH=CHCH₃.[1]
(b)A sample of this polymer has an average Mr of 112 000. Calculate the average number of but-2-ene monomer units in each chain. [Mr of C₄H₈ = 56.0][1]
(c)State the atom economy of any addition polymerisation and explain your answer.[2]
(d)Explain why the polymer from but-2-ene is saturated even though the monomer is unsaturated.[1]
Show answer
(a) –CH(CH₃)–CH(CH₃)–
B1.
(b) 2000
B1 112 000 ÷ 56.0 = 2000 (the repeat unit has the same formula as the monomer, ignoring end groups).
(c) 100 %; all the atoms of the monomer end up in the polymer – it is the only product.
B1 100 %; B1 only one product / no atoms lost.
(d) The π bond of each C=C breaks to form new C–C single bonds to neighbouring monomers.
B1.
Q10Addition polymers · Standard · Paper 2 style · 4 marks
(a)Write a balanced equation for the complete combustion of poly(ethene), (C₂H₄)ₙ.[1]
(b)Calculate the mass, in kg, of carbon dioxide produced when 14.0 kg of poly(ethene) burns completely. [Mr: C₂H₄ 28.0; CO₂ 44.0][2]
(c)Give one reason why poly(ethene) waste should not be burned in an open fire.[1]
Show answer
(a) (C₂H₄)ₙ + 3nO₂ → 2nCO₂ + 2nH₂O
B1.
(b) 44.0 kg
M1 14 000/28.0 = 500 mol repeat units → 1000 mol CO₂; A1 × 44.0 = 44 000 g = 44.0 kg.
Q11Addition polymers · Challenge · Paper 4 style · 5 marks
Perspex, a clear plastic used for shop signs, is an addition polymer made from methyl 2-methylpropenoate.
(a)Give the structural formula of the monomer, methyl 2-methylpropenoate.[1]
(b)Give the repeat unit of the polymer.[1]
(c)The polymer is heated with aqueous sodium hydroxide. Describe the change to the side groups and name the small molecule released.[2]
(d)Explain why the polymer backbone survives this treatment while a polyester backbone would not.[1]
Show answer
(a) CH₂=C(CH₃)COOCH₃
B1.
(b) –CH₂–C(CH₃)(COOCH₃)–
B1.
(c) The ester side groups are hydrolysed to sodium carboxylate groups (–COO⁻Na⁺); methanol is released. The main carbon chain is not broken.
B1 –COOCH₃ → –COO⁻Na⁺; B1 methanol.
(d) The backbone of the addition polymer contains only C–C bonds; in a polyester, ester links are in the main chain and are hydrolysed.
B1.
Q12Addition polymers · Challenge · Paper 2 style · 5 marks
A waste incinerator burns PVC pipe offcuts.
(a)Calculate the volume of hydrogen chloride, at r.t.p., released when 1.00 kg of PVC is burned completely. Assume each repeat unit –CH₂–CHCl– gives one HCl. [Mr of C₂H₃Cl = 62.5; molar gas volume 24.0 dm³][2]
(b)The HCl is removed by passing the gases through powdered calcium carbonate. Write the equation and calculate the mass of calcium carbonate needed. [Mr CaCO₃ = 100.1][3]
Show answer
(a) 384 dm³
M1 1000/62.5 = 16.0 mol; A1 × 24.0 = 384 dm³.
(b) CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂; 801 g
B1 equation; M1 8.00 mol CaCO₃; A1 801 g.
Q13Addition polymers · Challenge · Paper 4 style · 5 marks
(a)Prop-2-en-1-ol, CH₂=CHCH₂OH, can form an addition polymer. Give its repeat unit.[1]
(b)Suggest why the addition polymer from (a) can dissolve in water, whereas poly(propene) cannot.[2]
(c)Explain whether prop-2-en-1-ol alone could form a condensation polymer.[2]
Show answer
(a) –CH₂–CH(CH₂OH)–
B1.
(b) Each repeat unit has an –OH group that forms hydrogen bonds with water molecules; poly(propene) has only non-polar C–H/C–C bonds with instantaneous dipole forces.
B1 –OH hydrogen bonds with water; B1 poly(propene) non-polar.
(c) No – it has only one functional group (–OH) able to take part in condensation; a condensation polymer needs two reacting groups per monomer (or two different monomers).
B1 only one condensing group; B1 needs two functional groups.
Q14Condensation polymers (polyesters/polyamides) · Core · Paper 4 style · 6 marks
Nylon-6,6 is used to make fishing nets for boats in Karachi harbour.
(a)Name the two monomers used to make nylon-6,6.[2]
(b)Give the repeat unit of nylon-6,6.[2]
(c)Name the small molecule eliminated and the linkage formed.[2]
Show answer
(a) hexanedioic acid and hexane-1,6-diamine (1,6-diaminohexane)
B1 each.
(b) –NH(CH₂)₆NHCO(CH₂)₄CO–
B1 amide link shown; B1 correct numbers of CH₂ groups.
(c) water; amide (peptide) linkage –CONH–
B1 each.
Q15Condensation polymers (polyesters/polyamides) · Core · Paper 4 style · 5 marks
Plastic drinks bottles are made from PET, poly(ethylene terephthalate).
(a)Give the structural formulae of the two monomers used to make PET.[2]
(b)Give the repeat unit of PET.[2]
(c)Name the type of polymer.[1]
Show answer
(a) HOOC–C₆H₄–COOH (benzene-1,4-dicarboxylic acid) and HOCH₂CH₂OH (ethane-1,2-diol)
B1 each.
(b) –OC–C₆H₄–COO–CH₂CH₂–O–
B1 ester link; B1 rest correct.
(c) Polyester (condensation polymer)
B1.
Q16Condensation polymers (polyesters/polyamides) · Core · Paper 4 style · 4 marks
(a)State two differences between addition polymerisation and condensation polymerisation.[2]
(b)Classify each linkage: –COO– and –CONH–.[2]
Show answer
(a) Addition: monomers contain C=C, no other product, polymer has same empirical formula as monomer; condensation: monomers have two functional groups, a small molecule (e.g. H₂O or HCl) is eliminated.
Q17Condensation polymers (polyesters/polyamides) · Standard · Paper 4 style · 4 marks
In the 'nylon rope trick', nylon-6,6 is made at the interface between a solution of hexanedioyl dichloride in an organic solvent and an aqueous solution of hexane-1,6-diamine.
(a)Write the structural formula of hexanedioyl dichloride.[1]
(b)Name the small molecule eliminated when hexanedioyl dichloride reacts with hexane-1,6-diamine.[1]
(c)Give two advantages of using the diacyl dichloride rather than hexanedioic acid in a school laboratory.[2]
Show answer
(a) ClCO(CH₂)₄COCl
B1.
(b) hydrogen chloride (HCl)
B1.
(c) Reaction is fast at room temperature (no heating/catalyst needed); the reaction goes to completion (not an equilibrium).
1 mark each.
Q18Condensation polymers (polyesters/polyamides) · Standard · Paper 4 style · 5 marks
Kevlar is a polyamide used in bulletproof vests and cricket helmets.
(a)Give the structural formulae of the monomers used to make Kevlar.[2]
(b)Give the repeat unit of Kevlar.[1]
(c)Explain why Kevlar is very strong.[2]
Show answer
(a) H₂N–C₆H₄–NH₂ (benzene-1,4-diamine) and HOOC–C₆H₄–COOH (benzene-1,4-dicarboxylic acid) (or the diacyl dichloride)
B1 each.
(b) –NH–C₆H₄–NH–CO–C₆H₄–CO–
B1.
(c) Rigid, flat chains line up parallel; strong hydrogen bonds form between C=O of one chain and N–H of the neighbouring chain.
B1 linear rigid chains packed closely; B1 hydrogen bonds between chains (C=O···H–N).
Q19Condensation polymers (polyesters/polyamides) · Standard · Paper 4 style · 4 marks
PLA is made from maize or sugar cane and is used for disposable cups.
(a)Give the structural formula of 2-hydroxypropanoic acid (lactic acid).[1]
(b)Give the repeat unit of poly(lactic acid), PLA.[1]
(c)Explain how one monomer can form a condensation polymer on its own.[1]
(d)Explain why PLA is biodegradable.[1]
Show answer
(a) CH₃CH(OH)COOH
B1.
(b) –O–CH(CH₃)–CO–
B1.
(c) Each molecule has two different functional groups (–OH and –COOH), which react with groups on neighbouring molecules to form ester links.
B1.
(d) Its ester links can be hydrolysed (by water/enzymes/microorganisms).
B1.
Q20Condensation polymers (polyesters/polyamides) · Standard · Paper 4 style · 4 marks
Proteins are natural polyamides formed from amino acids.
(a)Draw (as text formulae) the two possible dipeptides formed from one glycine (H₂NCH₂COOH) and one alanine (H₂NCH(CH₃)COOH) molecule.[2]
(b)Give the repeat unit of poly(glycine).[1]
(c)Name the linkage formed between amino acids.[1]
Show answer
(a) H₂NCH₂CONHCH(CH₃)COOH and H₂NCH(CH₃)CONHCH₂COOH
B1 each.
(b) –NH–CH₂–CO–
B1.
(c) peptide (amide) link
B1.
Q21Condensation polymers (polyesters/polyamides) · Standard · Paper 4 style · 3 marks
A section of a polyamide is: –NH–(CH₂)₄–NH–CO–(CH₂)₈–CO–NH–(CH₂)₄–NH–CO–(CH₂)₈–CO–
(a)Identify the two monomers needed to make this polyamide. Give their structural formulae.[2]
(b)Give one other type of monomer that could replace the dicarboxylic acid.[1]
Show answer
(a) H₂N(CH₂)₄NH₂ (butane-1,4-diamine) and HOOC(CH₂)₈COOH (decanedioic acid)
B1 each.
(b) The diacyl dichloride, ClCO(CH₂)₈COCl
B1.
Q22Condensation polymers (polyesters/polyamides) · Standard · Paper 4 style · 5 marks
(a)For each monomer or pair of monomers, state whether it forms an addition or a condensation polymer: (i) propenamide, CH₂=CHCONH₂ (ii) hexane-1,6-diol and butanedioic acid (iii) 2-aminopropanoic acid (iv) tetrafluoroethene.[4]
(b)Give the repeat unit of the polymer formed in (ii).[1]
Show answer
(a) (i) addition (ii) condensation (iii) condensation (iv) addition
1 mark each.
(b) –O(CH₂)₆O–CO(CH₂)₂CO–
B1.
Q23Condensation polymers (polyesters/polyamides) · Challenge · Paper 4 style · 5 marks
A section of a polyester is: –O–CH₂CH₂CH₂–O–CO–(CH₂)₄–CO–O–CH₂CH₂CH₂–O–CO–(CH₂)₄–CO–
(a)Identify the products when the polyester is heated with dilute hydrochloric acid.[2]
(b)Identify the products when the polyester is heated with aqueous sodium hydroxide.[2]
(c)Name the type of reaction in (a) and (b).[1]
Show answer
(a) HOOC(CH₂)₄COOH (hexanedioic acid) and HOCH₂CH₂CH₂OH (propane-1,3-diol)
B1 each.
(b) NaOOC(CH₂)₄COONa (sodium hexanedioate) and HOCH₂CH₂CH₂OH
B1 salt; B1 diol.
(c) Hydrolysis
B1.
Q24Condensation polymers (polyesters/polyamides) · Challenge · Paper 4 style · 4 marks
(a)Show that the Mr of the repeat unit of nylon-6,6, C₁₂H₂₂N₂O₂, is 226.0.[1]
(b)A nylon-6,6 chain has an Mr of approximately 33 900. Calculate the number of repeat units in the chain (ignore the end groups).[1]
(c)Each repeat unit is formed from one diacid and one diamine molecule. Deduce how many water molecules were eliminated in forming one chain with this number of repeat units. Explain.[2]
Show answer
(a) 226.0
B1 12(12.0) + 22(1.0) + 2(14.0) + 2(16.0).
(b) 150
B1 33 900/226.0.
(c) 299
M1 one H₂O per amide link; A1 300 monomers joined by 299 links.
Q25Condensation polymers (polyesters/polyamides) · Challenge · Paper 4 style · 4 marks
(a)Give the repeat unit of nylon-6, made from 6-aminohexanoic acid, H₂N(CH₂)₅COOH.[1]
(b)A chain of nylon-6, H–[NH(CH₂)₅CO]₅₀₀–OH, has 500 repeat units. Calculate its Mr. [Mr of C₆H₁₁NO = 113.0; H₂O = 18.0][2]
(c)Explain why nylon-6 and nylon-6,6 have very similar properties.[1]
Show answer
(a) –NH–(CH₂)₅–CO–
B1.
(b) 56518
M1 500 × 113.0 = 56 500; A1 + 18.0 for end groups = 56518.
(c) Both have amide links regularly spaced along similar hydrocarbon chains, so similar hydrogen bonding between chains.
B1.
Q26Condensation polymers (polyesters/polyamides) · Challenge · Paper 4 style · 4 marks
(a)Write an equation for the complete hydrolysis of one repeat unit of nylon-6,6, –NH(CH₂)₆NHCO(CH₂)₄CO–, by hot concentrated hydrochloric acid.[2]
(b)Explain why the diamine is obtained as its salt.[1]
(c)Explain why nylon clothing is damaged by spills of acid.[1]
B1 diacid and diammonium salt products; B1 balanced (2H₂O and 2HCl).
(b) The amine groups are basic and are protonated by the excess acid.
B1.
(c) The amide links in the polymer chain are hydrolysed, breaking the chains and weakening the fibres.
B1.
Q27Polymer properties & degradability · Core · Paper 4 style · 4 marks
(a)Explain why polyesters and polyamides are biodegradable while poly(alkene)s are not.[2]
(b)Describe what is meant by a photodegradable polymer and give one structural feature that makes a polymer photodegradable.[2]
Show answer
(a) Polyesters/polyamides contain polar ester/amide links that can be hydrolysed (by enzymes/water); poly(alkene)s have only non-polar C–C and C–H bonds that are not attacked.
(b) One that breaks down when exposed to light (UV); it contains C=O groups that absorb UV and break bonds nearby.
B1 meaning; B1 C=O groups.
Q28Polymer properties & degradability · Standard · Paper 4 style · 4 marks
(a)Explain why nylon-6,6 has a much higher melting point than poly(ethene) of similar chain length.[2]
(b)Suggest why low-density poly(ethene), with many side branches, is softer than high-density poly(ethene).[2]
Show answer
(a) Nylon chains form hydrogen bonds between N–H and C=O of neighbouring chains; poly(ethene) has only weaker instantaneous dipole–induced dipole forces, needing less energy to overcome.
B1 hydrogen bonds in nylon; B1 only id–id forces in poly(ethene)/less energy.
(b) Branches stop the chains packing closely, so intermolecular forces are weaker and chains slide past each other more easily.
B1 packing; B1 weaker forces.
Q29Polymer properties & degradability · Standard · Paper 4 style · 5 marks
A large city such as Karachi produces thousands of tonnes of plastic waste every day.
(a)Give one advantage and one disadvantage of incinerating plastic waste.[2]
(b)Suggest why mixed plastic waste is difficult to recycle.[1]
(c)Explain why a bag made of a polyester would break down faster in a compost heap than one made of poly(propene).[2]
Show answer
(a) Advantage: energy released can generate electricity / reduces landfill volume. Disadvantage: releases CO₂ (greenhouse gas) and toxic gases such as HCl from PVC or CO.
B1 each.
(b) Different polymers have different properties/melting points and must be sorted first.
B1.
(c) Ester links are hydrolysed by water/enzymes from microorganisms; poly(propene) has no such polar links.
B1 hydrolysis of ester; B1 poly(propene) inert.
Q30Polymer properties & degradability · Challenge · Paper 4 style · 5 marks
A 12.0 g cup made of poly(lactic acid), PLA, is buried in an industrial compost heap. It loses 25 % of its mass in the first 30 days.
(a)Calculate the mass of the cup remaining after 90 days, assuming it continues to lose 25 % of its remaining mass every 30 days. Give your answer to 3 significant figures.[2]
(b)Name the type of reaction by which the PLA cup breaks down and the organic product.[2]
(c)Suggest why the same cup would break down more slowly in a dry landfill than in moist compost.[1]
