O Level Chemistry 5070 Paper 12, May/June 2026

The melting and boiling points of four substances are shown.

Which substance has the greatest rate of diffusion at $-50{}^{\circ }\text{C}$? A ammonia B hydrogen sulfide C propane D xenon

Which statement is correct? A Air is a mixture because it is made up entirely of different compounds. B Chlorine is an element because all of its atoms have the same atomic number and mass number. C Lead(II) bromide is a compound because it is impossible to separate it into its elements. D Stainless steel is a mixture because it can have a variable composition of different elements.

Which number is different for two isotopes of the same element? A the number of outer-shell electrons in each atom B the total number of electrons in each atom C the number of neutrons in each atom D the number of protons in each atom

Magnesium oxide has a high melting point. It is used to line the inside of furnaces that operate at high temperatures. Why does magnesium oxide have a high melting point? A It has metallic bonds. B It has strong forces between its molecules. C It is a simple molecular substance. D It is an ionic compound.

Which substance has a giant covalent structure and contains atoms of more than one element? A diamond B graphite C methane D silicon(IV) oxide

The displayed formula of a compound is shown. What is the empirical formula of the compound? A CHO B ${\text{C}}_2{\text{H}}_4\text{O}$ C ${\text{C}}_4{\text{H}}_8{\text{O}}_2$ D ${\text{CH}}_3{\text{COOCH}}_2{\text{CH}}_3$

An ionic compound contains only three elements, X, Y and Z. The compound has a ratio of one atom of X to one atom of Y to three atoms of Z. The average mass of the isotopes of element X is twice the mass of an atom of ${}_6^{12}\text{C}$. The average mass of the isotopes of element Y is equal to the mass of an atom of ${}_6^{12}\text{C}$. The relative atomic mass of Z is $\frac{4}{3}$ times the relative atomic mass of Y. What is the relative formula mass of the compound? A 26 B 42 C 52 D 84

Nitrogen monoxide and oxygen react to form nitrogen dioxide. $$2\text{NO}(\text{g})+{\text{O}}_2(\text{g})\to 2{\text{NO}}_2(\text{g})$$ What is the maximum volume of nitrogen dioxide that may be obtained when $1{\text{ dm}}^3$ of nitrogen monoxide reacts with $2{\text{ dm}}^3$ of oxygen when all volumes are measured at room temperature and pressure? A $1{\text{ dm}}^3$ B $2{\text{ dm}}^3$ C $3{\text{ dm}}^3$ D $4{\text{ dm}}^3$

During a titration, $25.0{\text{ cm}}^3$ of $0.050\text{ mol}\mathrm{/}{\text{dm}}^3$ aqueous sodium hydroxide, $\text{NaOH}$, reacts exactly with $20.0{\text{ cm}}^3$ of dilute phosphoric acid, ${\text{H}}_3{\text{PO}}_4$. $$3\text{NaOH}+{\text{H}}_3{\text{PO}}_4\to {\text{Na}}_3{\text{PO}}_4+3{\text{H}}_2\text{O}$$ What is the concentration of the dilute phosphoric acid? A $0.0208\text{ mol}\mathrm{/}{\text{dm}}^3$ B $0.0313\text{ mol}\mathrm{/}{\text{dm}}^3$ C $0.0625\text{ mol}\mathrm{/}{\text{dm}}^3$ D $0.1875\text{ mol}\mathrm{/}{\text{dm}}^3$

Concentrated and dilute aqueous $\text{XCl}$ are electrolysed separately using inert electrodes. X is a more reactive metal than sodium. Which row shows the products at the cathode and the anode?

Which statement comparing hydrogen–oxygen fuel cells with gasoline / petrol engines is correct? A A disadvantage of a hydrogen–oxygen fuel cell is that hydrogen is more difficult to store than gasoline / petrol. B A disadvantage of a hydrogen–oxygen fuel cell is that it is less efficient than a gasoline / petrol engine. C An advantage of a hydrogen–oxygen fuel cell is that it only produces carbon dioxide and water as products. D An advantage of gasoline / petrol engines is that they produce carbon monoxide by incomplete combustion.

Which row about endothermic reactions is correct?

Which property of a substance always remains the same during a physical change? A the density of the substance B the mass of the substance C the distance between the particles in the substance D the arrangement of particles in the substance

The reaction pathway diagram for both the catalysed and uncatalysed reactions between ${\text{N}}_2$ and ${\text{H}}_2$ in the Haber process is shown. What is the activation energy for the formation of ${\text{NH}}_3$ in the presence of a catalyst? A A B B C C D D

Elements X and Y react together in a reversible reaction to form ${\text{XY}}_2$. $$\text{X}+2\text{Y}\rightleftharpoons {\text{XY}}_2$$ $1.0\text{ mol}$ of X is mixed with $1.0\text{ mol}$ of Y and the mixture is left to react until an equilibrium position is reached. Which statements about this reaction are correct? 1 After the equilibrium position has been reached, the reaction stops. 2 At equilibrium, there is more than $0.5\text{ mol}$ of X present. 3 At equilibrium, there is less than $1.0\text{ mol}$ of ${\text{XY}}_2$ present. A 1, 2 and 3 B 2 and 3 only C 2 only D 3 only

Iodine, ${\text{I}}_2$, reacts with thiosulfate ions, ${\text{S}}_2{\text{O}}_3^{2-}$. $${\text{I}}_2(\text{aq})+2{\text{S}}_2{\text{O}}_3^{2-}(\text{aq})\to 2{\text{I}}^{-}(\text{aq})+{\text{S}}_4{\text{O}}_6^{2-}(\text{aq})$$ Which row is correct?

Citric acid is a soluble carboxylic acid. A student does two tests on separate samples of an aqueous solution of citric acid. Which row is correct?

Two solutions are prepared. • Solution P is $0.050\text{ mol}\mathrm{/}{\text{dm}}^3$ hydrochloric acid. • Solution Q is $0.100\text{ mol}\mathrm{/}{\text{dm}}^3$ butanoic acid. A $2\text{ cm}$ strip of magnesium ribbon is put into $100{\text{ cm}}^3$ of each solution. Fizzing is seen in both solutions, but the fizzing is faster in solution P than it is in solution Q. Which statement helps to explain this observation? A Magnesium reacts with solution P to form a salt, but does not form a salt with solution Q. B More particles are dissociated in solution P than are dissociated in solution Q. C Solution Q contains a stronger acid than solution P. D The particles are closer together in solution Q than they are in solution P.

The formulae of three oxides are listed. 1 $\text{CuO}$ 2 ${\text{SO}}_2$ 3 $\text{ZnO}$ Which oxides react with $\text{NaOH}(\text{aq})$ to form a salt? A 1, 2 and 3 B 2 and 3 only C 2 only D 3 only

Which statement about the arrangement of the elements in the Periodic Table is correct? A In all groups, the reactivity of the elements increases down the group. B The metallic character of the elements increases from left to right across a period. C The charge in the nucleus changes by the same amount from one element to the next down a group. D The charge in the nucleus changes by the same amount from one element to the next across a period.

Four statements about the elements in Group I of the Periodic Table are listed. 1 Potassium has a higher density than lithium. 2 Sodium has a higher melting point than lithium. 3 Lithium has more occupied electron shells than sodium. 4 Potassium is more reactive than sodium with water. Which statements are correct? A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

Rubidium is in Group I and fluorine is in Group VII of the Periodic Table. Which statements about these elements are correct? 1 Chlorine will displace fluorine from a solution of its salts. 2 Bromine is a liquid at r.t.p. 3 Rubidium is a soft metal. 4 Rubidium reacts more vigorously than potassium with water. A 1, 2 and 3 B 2, 3 and 4 C 2 and 3 only D 3 and 4 only

Which statement about transition elements is correct? A Their soluble salts usually form coloured aqueous solutions. B They are all in the same group of the Periodic Table. C They are non-metals with high melting points. D They can be mixed together to form compounds.

Which row describes an element in Group VIII of the Periodic Table?

The properties of four substances are shown. The letters in the table are not the formulae of the substances.

Which substances in the table may be metals? A W and X B W and Y C X and Z D Y and Z

Which statement about metals and alloys is correct? A Brass is a mixture of copper and tin. B Cutlery made of stainless steel contains iron and does not rust easily. C In pure metals, the negative ions are all the same size. D The hardness of iron is decreased by forming an alloy with chromium, nickel and carbon.

When element X is added to aqueous copper(II) sulfate, no effervescence is observed. The blue solution turns colourless. What is element X? A calcium B potassium C silver D zinc

Which substance is used for the electrodes when aluminium is extracted from its ore? A bauxite B carbon C cryolite D platinum

Water is added to anhydrous cobalt(II) chloride. Which colour change is seen? A blue to pink B blue to white C pink to blue D white to blue

Z is a pollutant gas that is formed in car engines. An aqueous solution of Z is acidic. Z is removed from the exhaust gases in a catalytic converter by reduction. What is Z? A CO B ${\text{N}}_2$ C ${\text{H}}_2\text{O}$ D ${\text{NO}}_2$

The structures of three compounds are shown. Which compounds are structural isomers of each other? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

X and Y are hydrocarbons obtained from the fractional distillation of petroleum. Their molecular formulae are shown. X: ${\text{C}}_{18}{\text{H}}_{38}$ Y: ${\text{C}}_8{\text{H}}_{18}$ Three statements are listed. 1 X and Y are both alkanes. 2 X has a higher viscosity than Y. 3 X comes from a fraction obtained higher in the fractionating column than Y. Which statements are correct? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

An unbranched alkene, ${\text{C}}_4{\text{H}}_8$, undergoes an addition reaction with bromine. What is the possible structure of the product? A ${\text{CH}}_3{\text{CHBrCH}}_2{\text{CH}}_2\text{Br}$ B ${\text{CH}}_3{\text{CHBrCHBrCH}}_3$ C ${\text{CH}}_2{\text{BrCH}}_2{\text{CH}}_2{\text{CH}}_2\text{Br}$ D ${\text{CH}}_3{\text{CH}}_2{\text{CH}}_2{\text{CH}}_2\text{Br}$

X mol of ethanol and X mol of propan-1-ol separately undergo complete combustion at the same temperature and pressure. The complete combustion of X mol of propan-1-ol requires $0.15\text{ mol}$ of oxygen more than the complete combustion of X mol of ethanol. What is the value of X? A 0.10 B 0.15 C 1.00 D 1.50

Ethanol can be converted by bacteria into vinegar, which contains ethanoic acid. Which type of chemical reaction is caused by the bacteria? A hydrogenation B neutralisation C oxidation D reduction

An ester has the formula ${\text{C}}_2{\text{H}}_5{\text{COOC}}_2{\text{H}}_5$. Which pair of compounds would react together to form this ester? A ethanoic acid and ethanol B ethanol and propanoic acid C propanoic acid and propanol D propanol and ethanoic acid

The formula of magnesium oxide can be investigated by using the fact that when magnesium is heated, it reacts with oxygen to form magnesium oxide. Which apparatus is used for this investigation? 1 gas syringe 2 balance 3 crucible A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

The diagram represents a chromatogram of the colourless acids in a drink. The chromatogram has been treated with a locating agent. A table of $R_{\text{f}}$ values for the possible acids is given.

Which acids are in the drink? A citric acid, malic acid and lactic acid B citric acid, malic acid and succinic acid C malic acid, lactic acid and succinic acid D tartaric acid, citric acid and malic acid

Which two pieces of apparatus are essential when separating a mixture of sodium chloride and barium sulfate? 1 filter funnel 2 filter paper 3 measuring cylinder 4 thermometer A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

An unknown salt, X, contains only one cation and only one anion. Aqueous sodium hydroxide is added to an aqueous solution of X. A white precipitate is formed that is soluble in excess aqueous sodium hydroxide. Aluminium foil is then added to the mixture and the mixture is warmed. A gas is produced that turns damp red litmus paper blue. Which ions are in salt X? A ${\text{NH}}_4^{+}$ and ${\text{SO}}_3^{2-}$ B ${\text{Al}}^{3+}$ and ${\text{NO}}_3^{-}$ C ${\text{Ca}}^{2+}$ and ${\text{NO}}_3^{-}$ D ${\text{Zn}}^{2+}$ and ${\text{SO}}_3^{2-}$