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Chemistry entrance exam, 2018 E.C. (2026)

Real questions from the Grade 12 university entrance exam in Chemistry, as students sat it in 2018 E.C. Every question comes with the correct answer and a worked explanation.

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Natural science stream
Who sits it
2018 E.C. (2026)
Exam year
69 questions with answers
In this set

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Answer each question yourself before opening the answer. The explanations point to the exact textbook section, so you know which page to reread when you miss one.

Question 1

Which one is a step-growth polymer?

A.Polyester
B.PTFE
C.Polystyrene
D.PVC

Show the answer and explanation

Answer: A Polyester

Why

A step-growth polymer builds up when two functional groups react and join, usually letting a small molecule such as water leave. A polyester forms when a diacid and a diol condense, so any two pieces that meet can link and the chain grows step by step. PTFE, polystyrene and PVC all come from monomers with a C=C bond that opens and adds onto a growing active end, which is chain growth. PTFE tempts because it is a famous plastic, but tetrafluoroethene polymerises through its double bond, not by condensation.

Question 2

All of the following are thermoplastic polymers; except:

A.Polyethylene
B.Nylon
C.Bakelite
D.Dacron

Show the answer and explanation

Answer: C Bakelite

Why

A thermoplastic softens every time it is heated, because its chains are separate and held together only by weak forces between them. Bakelite is made from phenol and formaldehyde into a rigid three dimensional network of covalent cross links, so heating cannot slide the chains past each other. It sets once and then chars instead of melting, which makes it a thermoset. Nylon looks like a candidate because it is also a condensation polymer, but its chains are linear, so it melts and can be reshaped.

Question 3

All of the following are addition polymer; except:

A.Dacron
B.PVC
C.Polypropylene
D.PMMA

Show the answer and explanation

Answer: A Dacron

Why

An addition polymer keeps every atom of its monomer, because the monomer carries a C=C bond that opens and adds on. PVC, polypropylene and PMMA all come from vinyl monomers in that way. Dacron is poly(ethylene terephthalate), made when a diacid and a diol join and a water molecule leaves at each link, so it is a condensation polymer. PMMA can look out of place because of its ester side group, but that ester is already present in the monomer and the chain still grows across the C=C bond.

Question 4

Which polymer is sold under the trade name Lucite or Plexiglas?

A.PTFE
B.PET
C.PMMA
D.Nylon-66

Show the answer and explanation

Answer: C PMMA

Why

Poly(methyl methacrylate) is the hard, glass clear plastic sold as Lucite or Plexiglas, used for aircraft windows, safety screens and signs. It is transparent, tough and lighter than glass. PET is also clear, which is why option B tempts, but PET is the bottle and fibre polyester known as Dacron, not the rigid glass substitute.

Question 5

Which one is the use of Teflon?

A.It is used as airplane windows.
B.It is used for making pipes and raincoats.
C.It is used for making parachutes and ropes.
D.It is used for coating cooking utensils.

Show the answer and explanation

Answer: D It is used for coating cooking utensils.

Why

Teflon is PTFE, a carbon chain wearing fluorine on every side. The C-F bonds are strong and the fluorine surface attracts other substances very weakly, so food and water do not stick and the coating survives cooking temperatures. That is why it lines frying pans and other cookware. Option A, aircraft windows, belongs to PMMA, the transparent plastic, while PTFE is waxy and opaque.

Question 6

The widely used PVC is a polymerized product of ______

A.CH₂ = CH₂
B.CH₂ = CCl₂
C.CH₂Cl – CH₂Cl
D.CH₂ = CHCl

Show the answer and explanation

Answer: D CH₂ = CHCl

Why

PVC stands for poly(vinyl chloride), so its monomer must be vinyl chloride, \( \mathrm{CH_2{=}CHCl} \). The double bond opens and the units join into a long chain carrying one chlorine on every second carbon. Option C, \( \mathrm{CH_2Cl-CH_2Cl} \), has the same atoms but no double bond, so there is nothing for the chain to add across. It is a saturated dichloroethane and cannot polymerise this way.

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Chemistry papers from other years

2017 E.C. (2025)2016 E.C. (2024)2015 E.C. (2023)2014 E.C. (2022)2013 E.C. (2021)2005 E.C. (2013)

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Are these the real 2018 E.C. Chemistry entrance exam questions?

Yes. They come from the national university entrance exam in Chemistry that students sat in 2018 E.C. (2026). Our set holds 69 of its questions, each with its answer and an explanation that points back to the textbook.

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Can I download the Chemistry 2018 E.C. paper as a PDF?

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