chermistry.com
Practice paper written from an analysis of every
O-Level Science (Chemistry) paper, 2010–2025

CANDIDATE
NAME

CENTRE
NUMBER

INDEX
NUMBER

SCIENCE (CHEMISTRY)

Specimen 2026

Paper 3 Chemistry

FORECAST PAPER · PAPER 3.5

For practice before the 2026 examination

1 hour 15 minutes

Candidates answer on the Question Paper.

No Additional Materials are required.

READ THESE INSTRUCTIONS FIRST

Write your name, centre number and index number in the boxes above.

You may use an HB pencil for any diagrams, graphs or rough working.

Write in dark blue or black pen.

Do not use staples, paper clips, glue or correction fluid.

The use of an approved scientific calculator is expected, where appropriate.

You may lose marks if you do not show your working or if you do not use appropriate units.

Section A
Answer all questions.
Write your answers in the spaces provided on the question paper.

Section B
Answer one question.
Write your answers in the spaces provided on the question paper.

A copy of the Data Sheet is printed on page 15.
A copy of the Periodic Table is printed on page 16.

The number of marks is given in brackets [ ] at the end of each question or part question.

The total mark for this paper is 65.

This document consists of 16 printed pages.

NOT AN OFFICIAL EXAMINATION PAPER
Written for classroom practice from the topic frequencies in the chermistry theory-paper analysis. It follows the layout, wording and mark scheme conventions of the O-Level Science (Chemistry) papers but is not set, endorsed or marked by any examination board.

Section AAnswer all the questions in the spaces provided.

A technician purifies a sample of Epsom salts, which is hydrated magnesium sulfate, that is mixed with insoluble grit.

The technician uses three stages.

(a)

Stage 1: The mixture is stirred with hot water. The Epsom salts dissolve but the grit does not.
State the name given to the water in this stage.

[1]

(b)

Stage 2: The hot mixture is poured through filter paper. The grit stays on the filter paper.
State the name of the technique used in this stage.

[1]

(c)

Stage 3: The clear solution that passes through the filter paper is left to cool slowly. Crystals of Epsom salts form.
State the name of the technique used in this stage.

[1]

[Total: 3]

The symbol for an ion of potassium is shown.

3919K⁺

(a)

State what the number 39 shows.

[1]

(b)

State what the number 19 shows.

[1]

(c)

Use your answers to (a) and (b) to deduce the number of neutrons and the number of electrons in one potassium ion.

number of neutrons =

number of electrons =

[2]

[Total: 4]

Iodine, water and methane are simple molecular substances. Table 3.1 shows some of their properties.

Table 3.1
substance	formula	melting point / °C	boiling point / °C
iodine	I₂	114	184
water	H₂O	0	100
methane	CH₄	−182	−162

(a)

Describe what is meant by the term covalent bond.

[1]

(b)

Use data from Table 3.1 to deduce which substance has the weakest forces of attraction between its molecules.
Give a reason for your answer.

[1]

(c)

When water boils, the covalent bonds inside the water molecules do not break.
Explain why. Use ideas about the forces between molecules in your answer.

[2]

(d)

Iodine does not conduct electricity when it is solid or when it is liquid.
Explain why.

[1]

(e)

Identify one substance in Table 3.1 that is a compound.
Give a reason for your answer.

[1]

[Total: 6]

Dilute hydrochloric acid reacts with metals, carbonates and bases.

A student adds a sample of each of three solids to separate portions of dilute hydrochloric acid. Table 4.1 shows some of the results.

(a)

Complete Table 4.1.

Table 4.1
solid added to dilute hydrochloric acid	observation	name of the gas formed
zinc	bubbles form and the zinc dissolves
sodium carbonate	bubbles form and the solid dissolves
magnesium oxide		no gas is formed

[3]

(b)

Describe a test for the gas formed when sodium carbonate reacts with dilute hydrochloric acid.
Include the result of the test.

[1]

(c)

Name the salt formed when magnesium oxide reacts with dilute hydrochloric acid.

[1]

[Total: 5]

Nitrogen monoxide, a colourless gas, reacts with oxygen to form nitrogen dioxide, a brown gas.

2NO(g) + O₂(g) → 2NO₂(g)

In experiment 1, a mixture of the two gases at 100 kPa and 25.0 °C is kept in a gas syringe. The temperature of the mixture rises to 26.2 °C as it turns brown. Table 5.1 shows five changes made to experiment 1, one at a time. Fig. 5.1 shows the particles in experiment 1 and after change 1.

Fig. 5.1

(a)

Complete Table 5.1 by putting one tick (✓) in each row to show the effect of the change on the rate of reaction.

Table 5.1
change made to experiment 1	rate increases	rate decreases	rate stays the same
1 the pressure is doubled by pushing in the plunger
2 the temperature is raised to 40 °C
3 the temperature is lowered to 10 °C
4 a larger volume of the same mixture is used, at the same pressure and temperature
5 more nitrogen monoxide is added at the same volume and temperature

[2]

(b)

Explain why the rate of reaction increases in change 1.
Use ideas about particles in your answer.

[2]

(c)

State whether the reaction is exothermic or endothermic. Give a reason for your answer.

[1]

[Total: 5]

Burning fuels releases gases into the air. Table 6.1 shows the amount of carbon dioxide in the air from 1960 to 2020. The unit ppm means parts per million.

Table 6.1
year	carbon dioxide in the air / ppm
1960	317
1980	339
2000	370
2020	414

(a)

Explain how the burning of fossil fuels has contributed to the trend shown in Table 6.1.

[1]

(b)

Use Table 6.1 to calculate the increase in the amount of carbon dioxide in the air from 1960 to 2020.

increase =ppm[1]

(c)

Car engines release oxides of nitrogen into the air.
State one natural source of oxides of nitrogen.

[1]

(d)

Bioethanol is a biofuel that can be used in place of petrol.
Name the plant, grown for its sugar, from which bioethanol is made.

[1]

(e)

A government replaces petrol with bioethanol made from the plant in (d), to slow down the trend shown in Table 6.1.
Explain how this could slow down the trend. Use ideas about photosynthesis in your answer.

[1]

[Total: 5]

A white crust forms on the inside of a pipe. A technician dissolves a small sample of the crust, X, in a large volume of water. X contains one cation and one anion. Table 7.1 shows the tests on the solution and the results.

Table 7.1
test	what is added to a solution of X	result
1	add aqueous sodium hydroxide until it is in excess	a white precipitate that does not dissolve in excess
2	add aqueous ammonia until it is in excess	no precipitate; the solution stays colourless
3	add dilute nitric acid, then aqueous barium nitrate	a white precipitate

(a)

Name the cation in X. Use the results of tests 1 and 2 to explain your answer.

[2]

(b)

A student says that the white precipitate in test 1 is aluminium hydroxide.
Use your knowledge of the tests for aluminium ions to explain why the student is wrong.

[2]

(c)

Name the anion in X.

[1]

(d)

Name the white precipitate in test 3.

[1]

(e)

Name the compound X.

[1]

(f)

Write a balanced chemical equation, including state symbols, for the reaction in test 3.

[3]

[Total: 10]

Lead can be obtained by heating lead(II) oxide, PbO, with carbon.

2PbO(s) + C(s) → 2Pb(l) + CO₂(g)

A worker heats 44.6 g of lead(II) oxide with 3.00 g of carbon.

[A_r: C, 12; O, 16; Pb, 207]

(a)

Calculate the relative formula mass, M_r, of lead(II) oxide.

M_r =[1]

(b)

Calculate the amount, in moles, of lead(II) oxide in 44.6 g.

amount =mol[1]

(c)

Use your answer to (b) and the equation to deduce which reactant is in excess.

[1]

(d)

Use your answer to (b) and the equation to calculate the mass of lead formed.

mass =g[2]

(e)

Use your answer to (b) and the equation to calculate the mass of carbon that is left over at the end of the reaction.

mass =g[2]

[Total: 7]

Ethene, C₂H₄, and propene, C₃H₆, are alkenes that are used to make addition polymers.

(a)

Complete Table 9.1 by putting a tick (✓) in each box that applies.

Table 9.1
statement	ethene	propene	poly(ethene)
it is a hydrocarbon
it decolourises aqueous bromine
it is a saturated compound
it has very large molecules

[4]

(b)

Deduce the molecular formula of the alkene that has five carbon atoms.

[1]

(c)

But-1-ene, CH₂=CHCH₂CH₃, is a monomer. It forms an addition polymer.
Draw a section of the structure of this polymer that shows two repeat units.
You may write the ethyl group as C₂H₅.

[2]

(d)

Suggest why plastic bags made from addition polymers do not rot when buried in the ground.

[1]

(e)

Write a balanced chemical equation for the reaction of propene with bromine.

[1]

(f)

Draw the displayed formula of ethanol, C₂H₅OH.

[1]

[Total: 10]

Section BAnswer one question from this section.

The Group 1 metals react with water to form alkaline solutions.

Table 10.1 shows the densities of four Group 1 metals and of water.

Table 10.1
substance	density / g / cm³
lithium	0.53
sodium	0.97
potassium	0.86
rubidium	1.53
water	1.00

A student reacts lithium with water using the apparatus in Fig. 10.1. The piece of lithium is wrapped in wire gauze so that it stays under the funnel. The gas produced is collected in the test-tube.

Fig. 10.1

(a)

Use data from Table 10.1 to identify the Group 1 metals that float on water. State why these metals float.

[2]

(b)

Lithium reacts with water to form hydrogen and one other product. Name the other product.

[1]

(c)

Potassium is added to water instead of lithium. State one difference that you would observe.

[1]

(d)

The melting point of lithium is 181 °C and the melting point of sodium is 98 °C. Predict the melting point of potassium.

melting point =°C[1]

(e)

Sodium and potassium are Group 1 elements.

(i)

Sodium has proton number 11. State the electronic configuration of sodium.

[1]

(ii)

Predict the formula of potassium oxide.

[1]

(f)

Lithium burns in oxygen to form lithium oxide, Li₂O, an ionic compound. Draw a 'dot-and-cross' diagram to show the bonding in lithium oxide. Show only the outer shell electrons. Include the charge on each ion.

[Proton numbers: Li, 3; O, 8]

[2]

(g)

The equation for the reaction between lithium and oxygen is shown.

4Li + O₂ → 2Li₂O

Explain why oxygen is reduced in this reaction. Use ideas about electron transfer in your answer.

[1]

[Total: 10]

Metals can be placed in order of reactivity by comparing how they react with steam.

A student heats equal-sized pieces of four metals, one at a time, in steam using the apparatus in Fig. 11.1. The gas produced is collected in a gas syringe for 2 minutes. Fig. 11.1 shows the syringe at the end of the experiment with magnesium. Table 11.1 shows the results.

Fig. 11.1

Table 11.1
metal	observation	volume of gas in 2 minutes / cm³
magnesium	burns with a bright white flame	see Fig. 11.1
zinc	glows when heated strongly	14
iron	glows faintly when heated strongly	5
copper	no change	0

(a)

Name the gas collected in the syringe. Use Fig. 11.1 to state the volume of this gas collected in 2 minutes.

name of gas = .............. volume = .............. cm³

[2]

(b)

State which of the four metals is the least reactive. Use data from Table 11.1 to give a reason for your answer.

[1]

(c)

Magnesium reacts with steam to form hydrogen and a white solid. Name the white solid.

[1]

(d)

Calcium reacts with cold water. Magnesium does not react with cold water. Predict where calcium is placed in the order of reactivity of calcium, magnesium, zinc, iron and copper.

[1]

(e)

A student sets up four test-tubes, each containing an iron nail, as described in Table 11.2.

Table 11.2
statement	tick (✓)
The nail is in dry air above anhydrous calcium chloride.
The nail is in tap water in an open test-tube.
The nail is in boiled water covered with a layer of oil.
The nail is in damp air in an open test-tube.

(i)

Tick the two rows that describe nails that rust.

[1]

(ii)

Explain why the nail in the boiled water covered with oil does not rust.

[1]

(f)

Oxygen from the air is needed for iron to rust. Oxygen exists as molecules, O₂, in which the two atoms are joined by covalent bonds. Complete the 'dot-and-cross' diagram in Fig. 11.2 by drawing the outer shell electrons of both atoms. Use dots for one atom and crosses for the other atom.

[Proton number: O, 8]

Fig. 11.2

[2]

(g)

The equation for the reaction between magnesium and steam is shown.

Mg + H₂O → MgO + H₂

In steam, hydrogen has the oxidation state +1. Complete the two lines to show the oxidation and the reduction in this reaction.

oxidation: the oxidation state of magnesium changes from .............. to ..............

reduction: the oxidation state of hydrogen changes from +1 to ..............

[1]

[Total: 10]

Data Sheet

Colours of Some Common Metal Hydroxides

aluminium hydroxide	white
calcium hydroxide	white
copper(II) hydroxide	light blue
iron(II) hydroxide	green
iron(III) hydroxide	red-brown
zinc hydroxide	white

The Periodic Table of Elements

Group

Key

hydrogen

helium

lithium

beryllium

proton (atomic) number

atomic symbol

name

relative atomic mass

boron

carbon

nitrogen

oxygen

fluorine

neon

sodium

magnesium

aluminium

silicon

phosphorus

sulfur

chlorine

35.5

argon

potassium

calcium

scandium

titanium

vanadium

chromium

manganese

iron

cobalt

nickel

copper

zinc

gallium

germanium

arsenic

selenium

bromine

krypton

rubidium

strontium

yttrium

zirconium

niobium

molybdenum

technetium

–

ruthenium

101

rhodium

103

palladium

106

silver

108

cadmium

112

indium

115

tin

119

antimony

122

tellurium

128

iodine

127

xenon

131

caesium

133

barium

137

57–71

lanthanoids

hafnium

178

tantalum

181

tungsten

184

rhenium

186

osmium

190

iridium

192

platinum

195

gold

197

mercury

201

thallium

204

lead

207

bismuth

209

polonium

–

astatine

–

radon

–

francium

–

radium

–

89–103

actinoids

104

rutherfordium

–

105

dubnium

–

106

seaborgium

–

107

bohrium

–

108

hassium

–

109

meitnerium

–

110

darmstadtium

–

111

roentgenium

–

112

copernicium

–

113

nihonium

–

114

flerovium

–

115

moscovium

–

116

livermorium

–

117

tennessine

–

118

oganesson

–

lanthanoids

lanthanum

139

cerium

140

praseodymium

141

neodymium

144

promethium

–

samarium

150

europium

152

gadolinium

157

terbium

159

dysprosium

163

holmium

165

erbium

167

thulium

169

ytterbium

173

lutetium

175

actinoids

actinium

–

thorium

232

protactinium

231

uranium

238

neptunium

–

plutonium

–

americium

–

curium

–

berkelium

–

californium

–

einsteinium

–

100

fermium

–

101

mendelevium

–

102

nobelium

–

103

lawrencium

–

The volume of one mole of any gas is 24 dm³ at room temperature and pressure (r.t.p.).

The Avogadro constant, L = 6.02 × 10²³ mol^-1