O Level Chemistry 5070 Paper 11, May/June 2026

A gas occupies a volume of $2.0{\text{ dm}}^3$ at room temperature and pressure. Which changes in the conditions would both decrease the volume occupied by the gas?

In the diagrams, atoms of different elements are represented by different sizes of circle. Which diagram represents a mixture of nitrogen and argon? A B C D

The difference between the nucleon number and the proton number indicates the number of ......1...... in the atom. Atoms that have different nucleon numbers but the same proton number are called ......2...... . Which words correctly complete gaps 1 and 2?

The diagram shows the relative mass and the relative charge of two particles present in atoms and ions. Which of these particles are present in a hydrogen atom and in a hydrogen ion?

Which diagram represents magnesium oxide? A B C D

Three statements about graphite and diamond are listed. 1 Graphite and diamond both have giant covalent structures. 2 Graphite is used as a lubricant; diamond is not used as a lubricant. 3 Graphite is used to make electrodes; diamond is not used to make electrodes. Which statements are correct? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Solid element X consists of a lattice of ions surrounded by a 'sea' of delocalised electrons. Which row is correct?

Which definition of the empirical formula of a compound is correct? A the number and type of different atoms or ions in one mole of the compound B the number of different atoms or ions in one mole of the compound C the relative number of bonds between the different atoms or ions in the compound D the simplest whole number ratio of the different atoms or ions in the compound

Hydrated magnesium sulfate has the formula ${\text{MgSO}}_4\cdot 7{\text{H}}_2\text{O}$. [$A_{\text{r}}$: Mg, 24; S, 32; O, 16; H, 1] Which mass of hydrated magnesium sulfate is needed to make $250{\text{ cm}}^3$ of a solution containing $0.50\text{ moles per litre}$ of magnesium ions, ${\text{Mg}}^{2+}$? A 15.00 B 30.75 C 61.50 D 123.0

A $3.00\text{ g}$ sample of copper ore containing copper(II) carbonate, ${\text{CuCO}}_3$, and inert rock is heated until there is no change in mass. When cool, the residue weighs $2.20\text{ g}$. The equation shows the decomposition of the carbonate. $${\text{CuCO}}_3\to \text{CuO}+{\text{CO}}_2$$ What is the percentage purity of the ore? A 48.5% B 71.5% C 75.2% D 77.4%

A compound contains $40.0\mathrm{\%}$ carbon, $6.7\mathrm{\%}$ hydrogen and $53.3\mathrm{\%}$ oxygen by mass. The relative molecular mass of the compound is between 55 and 65. What is the molecular formula of the compound? A ${\text{CH}}_2\text{O}$ B ${\text{C}}_2{\text{H}}_4\text{O}$ C ${\text{C}}_2{\text{H}}_4{\text{O}}_2$ D ${\text{C}}_2{\text{H}}_6{\text{O}}_2$

Molten sodium chloride is electrolysed. Which change occurs at the cathode? A Sodium ions are oxidised. B Sodium ions are reduced. C Chloride ions are oxidised. D Chloride ions are reduced.

Three statements about hydrogen–oxygen fuel cells are listed. 1 They produce less carbon dioxide than petrol engines. 2 They produce hydrogen and oxygen as the only chemical products. 3 They are used to generate electricity. Which statements are correct? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Some bond energies are given in the table.

Ethene burns in oxygen to form carbon dioxide and water. $${\text{C}}_2{\text{H}}_4+3{\text{O}}_2\to 2{\text{CO}}_2+2{\text{H}}_2\text{O}$$ What is the enthalpy change of this reaction? A –1583 kJ / mol B –1318 kJ / mol C –655 kJ / mol D –390 kJ / mol

A student investigates the rate of reaction between magnesium and excess dilute hydrochloric acid by doing three experiments. The student measures the volume of hydrogen gas produced at regular intervals. The results of the three experiments are shown. Which statement is correct assuming that all other conditions remain the same in each case? A Experiment 1 uses the same amount of magnesium as experiment 3, but twice the concentration of hydrochloric acid. B Experiment 1 uses the same amounts of reactants as experiment 2, but at a higher temperature. C Experiment 2 uses twice the amount of magnesium as experiment 3, but in the presence of a catalyst. D Experiment 3 uses the same amounts of reactants as experiment 2, but with powdered magnesium instead of magnesium ribbon.

When bismuth(III) chloride, ${\text{BiCl}}_3$, is added to water, a reaction occurs and a white precipitate of $\text{BiOCl}$ is formed. $${\text{BiCl}}_3(\text{aq})+{\text{H}}_2\text{O}(\text{l})\rightleftharpoons \text{BiOCl}(\text{s})+2\text{HCl}(\text{aq})$$ Which changes increase the mass of white precipitate formed? 1 adding more water 2 adding aqueous sodium hydroxide 3 adding dilute hydrochloric acid A 1 and 2 B 1 and 3 C 1 only D 2 and 3

The Haber process is used to make ammonia. Which catalyst is used in the Haber process? A iron B nickel C platinum D vanadium(V) oxide

Copper(II) hydroxide is insoluble in water. Rubidium hydroxide is soluble in water. Which row describes copper(II) hydroxide and rubidium hydroxide?

Which ion is present in dilute aqueous propanoic acid? A ${\text{CH}}_3{\text{CH}}_2{\text{COO}}^{+}$ B ${\text{CH}}_3{\text{CH}}_2{\text{CH}}_2{\text{COO}}^{-}$ C ${\text{H}}^{+}$ D ${\text{H}}^{-}$

Caesium is an element in Group I and Period 6 of the Periodic Table. Which statement is correct? A Caesium is more dense than lithium. B Caesium reacts with water to produce a solution with a pH less than 7. C Caesium reacts less vigorously than lithium with water. D Caesium melts at a higher temperature than lithium.

Aqueous bromine is added to aqueous potassium iodide. Which colour is the aqueous bromine and what is the final colour of the reaction mixture?

Properties of four elements are listed. Only one of the elements is a transition element. Which element is the transition element?

A student makes three statements about the elements in Group VIII of the Periodic Table. 1 Their atoms all have eight electrons in the outer shell. 2 Their molecules are covalently bonded. 3 They all have a boiling point below room temperature. Which statements are correct? A 1 and 2 B 1 and 3 C 2 and 3 D 3 only

Which statement about aluminium is correct? A It is used in the electrical wiring of houses because of its high resistance to corrosion and poor electrical conductivity. B It is used in the manufacture of aircraft because of its high ductility and high density. C It is used in overhead electrical cables because of its good electrical conductivity and poor resistance to corrosion. D It is used in food containers because of its high malleability and high resistance to corrosion.

Which statement is correct? A Copper displaces magnesium from aqueous magnesium sulfate. B Carbon reacts with magnesium oxide; carbon dioxide is one product of this reaction. C Iron displaces silver from aqueous silver nitrate. D Hydrogen reacts with zinc oxide; water is one product of this reaction.

The diagram shows how an underwater iron pipe can be protected from rusting. Metal Z can be ......1...... because it is ......2...... reactive than iron. Which words correctly complete gaps 1 and 2?

Process 1: Iron is extracted from hematite in a blast furnace. Process 2: Aluminium is extracted from purified bauxite in an electrolytic cell. Which statements are correct for both processes? 1 An oxide in the ore is reduced. 2 Carbon reacts with oxygen to form carbon dioxide. 3 Impurities are removed as slag. 4 Thermal decomposition takes place. A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

A solution of sodium chloride in water is tested with anhydrous copper(II) sulfate and anhydrous cobalt(II) chloride. The boiling point of the solution at 1 atm pressure is also measured. Which row is correct?

NPK fertilisers are used to provide three elements for improved plant growth. Which mixture of compounds contains all three of these elements? A ammonium nitrate and calcium phosphate B calcium phosphate and potassium sulfate C potassium nitrate and calcium phosphate D potassium sulfate and ammonium sulfate

Which row about carbon dioxide and methane is correct?

The structural formulae of three compounds are listed. 1 ${\text{CH}}_3\text{COOH}$ 2 ${\text{HCOOCH}}_3$ 3 ${\text{CH}}_3{\text{CH}}_2\text{OH}$ Which compounds are carboxylic acids? A 1, 2 and 3 B 1 and 2 only C 1 only D 2 and 3 only

A hydrocarbon, Q, has molecular formula ${\text{C}}_x{\text{H}}_y$. Q reacts with hydrogen to form a single product with molecular formula ${\text{C}}_x{\text{H}}_{y+2}$. Which statement about Q is correct? A Q does not burn in air. B Q is a saturated hydrocarbon. C Q reacts with bromine to form a single product with molecular formula ${\text{C}}_x{\text{H}}_{y-1}\text{Br}$. D Q reacts with steam to form a single product with molecular formula ${\text{C}}_x{\text{H}}_{y+2}\text{O}$.

Propane is an alkane that can react with chlorine. Which statement is correct? A Two of the products of the reaction between propane and chlorine have the molecular formula ${\text{C}}_3{\text{H}}_7\text{Cl}$. B Each carbon atom in a propane molecule has only one pair of bonding electrons. C The reaction between propane and chlorine is an example of photosynthesis with ultraviolet radiation providing the activation energy. D Propane can undergo combustion, substitution and addition reactions depending on the conditions.

How can alkenes be manufactured? A by polymerisation reactions B by the addition of hydrogen to unsaturated vegetable oils C by the combustion of alkanes D by the cracking of hydrocarbons

The displayed formula of an ester is shown. Which acid and which alcohol react to form this ester?

Nylon and poly(ethene) are formed by polymerisation reactions. Which other products, if any, are formed during the two polymerisation reactions?

Solution X is made by adding solid glucose to liquid ethanol in a beaker. This mixture is stirred. After stirring, solid glucose is visible at the bottom of the beaker. The amount of solid glucose present is not changed by repeated stirring. Which substance is the solute and how is solution X described?

Which piece of apparatus is used to add one reagent to another reagent during a titration? A burette B conical flask C measuring cylinder D volumetric pipette

Chromatography is used to separate and identify dyes in a mixture. Which statement is correct? A A dye can have an $R_{\text{f}}$ value of 1.2. B A dye can have different $R_{\text{f}}$ values with different solvents. C All blue dyes have the same $R_{\text{f}}$ value. D Chromatography can only be used for coloured substances such as dyes.

J is an aqueous solution. When aqueous sodium hydroxide is added to J, a green precipitate is formed. The resulting mixture is heated, and no gas is formed. Aluminium foil is added to the warmed mixture. A gas is formed that turns damp red litmus paper blue. Which ions does J contain? A ${\text{Fe}}^{3+}$ and ${\text{NH}}_4^{+}$ B ${\text{Fe}}^{3+}$ and ${\text{NO}}_3^{-}$ C ${\text{Fe}}^{2+}$ and ${\text{NH}}_4^{+}$ D ${\text{Fe}}^{2+}$ and ${\text{NO}}_3^{-}$