IGCSE Chemistry 0620 Paper 23, May/June 2024

Sodium chloride is a liquid at 900 °C. Which row describes the arrangement and the motion of the particles in sodium chloride at 900 °C?

Hydrogen chloride gas, $\mathrm{H}\mathrm{C}\mathrm{l}$, reacts with ammonia gas, ${\mathrm{N}\mathrm{H}}_3$, to form solid ammonium chloride. The apparatus is set up as shown. After a few minutes, a white cloud of solid ammonium chloride forms where the two gases meet. The experiment is repeated using hydrogen bromide gas, $\mathrm{H}\mathrm{B}\mathrm{r}$, in place of hydrogen chloride. How far along the tube does the white cloud of solid ammonium bromide form?

Substances P and Q both conduct electricity. P is a mixture of two different types of atom. Q is made of only one type of atom. Which row describes P and Q?

An atom of element R contains 15 protons, 16 neutrons and 15 electrons. What is R? A gallium B phosphorus C sulfur D zinc

Which molecule contains a double covalent bond between two atoms of the same element? A carbon dioxide B ethanol C ethene D nitrogen

Silicon(IV) oxide is a covalently bonded compound. Which statements are correct? 1 Silicon atoms form four single bonds in silicon(IV) oxide. 2 Oxygen atoms form two double bonds in silicon(IV) oxide. 3 Silicon(IV) oxide has a high melting point. 4 Silicon(IV) oxide contains one silicon atom and four oxygen atoms. A 1 and 2 B 1 and 3 C 2 and 3 D 3 and 4

The equation for the reaction of iron(III) oxide with carbon monoxide is shown. $${\mathrm{F}\mathrm{e}}_2{\mathrm{O}}_3+3\mathrm{C}\mathrm{O}\to 2\mathrm{F}\mathrm{e}+3{\mathrm{C}\mathrm{O}}_2$$ What is the percentage yield of iron when $16.8\text{ g}$ of carbon monoxide reacts completely with iron(III) oxide to form $8.96\text{ g}$ of iron? A 26.7% B 40.0% C 53.3% D 80.0%

What is the volume of $14.5\text{ g}$ of gaseous butane, ${\mathrm{C}}_4{\mathrm{H}}_{10}$, at room temperature and pressure? A $96.0{\text{ cm}}^3$ B $6.0{\text{ cm}}^3$ C $96.0{\text{ dm}}^3$ D $6.0{\text{ dm}}^3$

Aqueous copper(II) sulfate is electrolysed using copper electrodes. Which statement describes what happens during the electrolysis? A Copper atoms gain electrons at the cathode and copper(II) ions lose electrons at the anode. B Electrons move in the external circuit from the positive electrode to the negative electrode. C Copper(II) ions move through the electrolyte from the cathode to the anode. D Copper is formed at the cathode and oxygen is formed at the anode.

Electrolysis is carried out on concentrated aqueous potassium bromide using inert electrodes. Which products are formed at the anode and the cathode?

Hydrogen–oxygen fuel cells and gasoline are each used to power cars. Which statement describes an advantage of using hydrogen–oxygen fuel cells in cars in comparison with gasoline engines? A Hydrogen is a non-renewable resource. B Hydrogen is produced during the fractional distillation of petroleum. C Hydrogen–oxygen fuel cells do not release carbon dioxide. D Hydrogen–oxygen fuel cells need electricity to work.

Plant cells use energy from sunlight for photosynthesis. Which row describes and explains the energy change that occurs?

Two different experiments are done to find the enthalpy change, $\mathrm{\Delta }H$, of each reaction. The temperature of each reaction mixture is measured at the beginning of the reaction and after 3 minutes. Which row gives the correct sign for the value of $\mathrm{\Delta }H$ for each experiment and identifies if the reaction is endothermic or exothermic?

The reaction pathway diagram for an endothermic reaction is shown. $u$, $v$ and $w$ are known energy values. Which diagram shows the reaction pathway diagram when a catalyst is used in the reaction?

Which process is a physical change? A burning a piece of magnesium B reacting calcium carbonate with hydrochloric acid C melting an ice cube D the rusting of an iron nail

The Contact process is used to convert sulfur dioxide to sulfur trioxide. Vanadium(V) oxide is the catalyst in this process. $$2{\mathrm{S}\mathrm{O}}_2(\mathrm{g})+{\mathrm{O}}_2(\mathrm{g})\rightleftharpoons 2{\mathrm{S}\mathrm{O}}_3(\mathrm{g})$$ The forward reaction in this equilibrium is exothermic. Which statements about this process are correct? 1 The catalyst increases the rate of both the forward and backward reactions. 2 A low pressure increases the yield of sulfur trioxide. 3 A low pressure is used to keep the costs low. 4 A high temperature increases the yield of sulfur trioxide. A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

The equation for the decomposition of hydrogen peroxide, ${\mathrm{H}}_2{\mathrm{O}}_2$, is shown. $$2{\mathrm{H}}_2{\mathrm{O}}_2\to 2{\mathrm{H}}_2\mathrm{O}+{\mathrm{O}}_2$$ In an experiment, the total volume of oxygen produced is $100{\text{ cm}}^3$. The experiment is repeated using $1.00\text{ g}$ of a solid catalyst. All other conditions remain the same. Which row describes the total volume of oxygen and the mass of the catalyst at the end of the second experiment?

Nitrogen reacts with hydrogen to form ammonia in the presence of an iron catalyst. The reaction is reversible. $${\mathrm{N}}_2(\mathrm{g})+3{\mathrm{H}}_2(\mathrm{g})\rightleftharpoons 2{\mathrm{N}\mathrm{H}}_3(\mathrm{g})$$ Which statement about this reaction is correct? A The iron catalyst decreases the activation energy of only the forward reaction. B When equilibrium is reached, the forward reaction has stopped. C When the pressure changes, the concentration of ammonia at equilibrium remains constant. D Nitrogen and hydrogen never completely convert to ammonia.

The equation for a redox reaction is shown. $${\mathrm{H}}_2{\mathrm{O}}_2+2\mathrm{K}\mathrm{I}+{\mathrm{H}}_2{\mathrm{S}\mathrm{O}}_4\to {\mathrm{I}}_2+{\mathrm{K}}_2{\mathrm{S}\mathrm{O}}_4+2{\mathrm{H}}_2\mathrm{O}$$ Potassium iodide is ...... 1 ...... agent in this reaction because iodide ions ...... 2 ...... electrons. Which words complete gaps 1 and 2?

Element E is in Group II of the Periodic Table. Which row describes element E and its oxide?

Lead(II) iodide is formed as a precipitate in the reaction shown. $$\mathrm{P}\mathrm{b}({\mathrm{N}\mathrm{O}}_3{)}_2(\mathrm{a}\mathrm{q})+2\mathrm{N}\mathrm{a}\mathrm{I}(\mathrm{a}\mathrm{q})\to {\mathrm{P}\mathrm{b}\mathrm{I}}_2(\mathrm{s})+2{\mathrm{N}\mathrm{a}\mathrm{N}\mathrm{O}}_3(\mathrm{a}\mathrm{q})$$ Which method is used to separate the lead(II) iodide from the mixture? A crystallisation B distillation C evaporation D filtration

Which statement explains why sulfur, S, has similar chemical properties to selenium, Se? A They both have the same number of electrons in their outer electron shell. B They are both solids at room temperature and pressure. C They are both non-metals. D They both form negative ions.

Atoms of sodium, rubidium and element Q each have one outer shell electron. Some properties of these elements are shown.

What is Q? A hydrogen B lithium C potassium D caesium

Which statement about elements in Group VIII of the Periodic Table is correct? A They all have a full outer shell of electrons. B They all react with Group I elements to form ionic compounds. C They are all diatomic molecules. D They are all liquids at room temperature and pressure.

The electrical conductivity of magnesium is tested. Magnesium is then added to dilute sulfuric acid. A gas, W, is produced. Which row describes the electrical conductivity of magnesium and identifies W?

Aluminium metal is extracted from its purified ore by electrolysis. Which statement about the electrolyte in this process is correct? A The electrolyte is purified molten bauxite only. B The electrolyte is purified bauxite dissolved in molten cryolite. C The electrolyte is purified molten cryolite only. D The electrolyte is purified cryolite dissolved in molten bauxite.

Part of the reactivity series is shown. potassium X calcium Y aluminium Which metals are represented by X and Y?

Some substances found in water extracted from a river are listed. 1 plastics 2 nitrates 3 oxygen Which substances are harmful to aquatic life? A 1 and 2 B 1 and 3 C 2 only D 3 only

Car engines which use gasoline as a fuel produce oxides of nitrogen. Oxides of nitrogen are removed from the exhaust gases. Which statements about the formation or removal of oxides of nitrogen are correct? 1 Gasoline reacts with nitrogen in the air to produce oxides of nitrogen. 2 Gasoline contains nitrogen. 3 Nitrogen and oxygen react at high temperatures to produce oxides of nitrogen. 4 Nitrogen monoxide, $\mathrm{N}\mathrm{O}$, reacts with carbon monoxide, $\mathrm{C}\mathrm{O}$, in a catalytic converter. A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

Which structures represent a pair of structural isomers? 1 ${\mathrm{C}\mathrm{H}}_3{\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}}_3$ 2 ${\mathrm{C}\mathrm{H}}_3{\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}}_2\mathrm{C}\mathrm{H}({\mathrm{C}\mathrm{H}}_3{)}_2$ 3 ${\mathrm{C}\mathrm{H}}_3\mathrm{C}\mathrm{H}({\mathrm{C}\mathrm{H}}_3){\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}}_3$ 4 ${\mathrm{C}\mathrm{H}}_3\mathrm{C}\mathrm{H}({\mathrm{C}\mathrm{H}}_3){\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}}_3$ A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

Alkanes are a homologous series of hydrocarbons. The table shows the names and boiling points of the first four members of this series.

Pentane is the next member of the series. Which row gives the molecular formula and the boiling point of pentane?

Which displayed formula represents the ester formed by the reaction of propan-1-ol with ethanoic acid?

Ethanol can be manufactured by fermentation and by the catalytic addition of steam to ethene. Which statement identifies an advantage of using one of these methods? A Catalytic addition requires a high temperature and pressure. B Ethanol produced by fermentation is extracted by distillation. C Fermentation is a batch process. D The raw material in fermentation is a renewable resource.

Which statement about carboxylic acids is correct? A They react with alkalis to form a salt and water. B They react with metals to form a salt and water. C They react with metal carbonates to form a salt, water and hydrogen. D The general formula for carboxylic acids is ${\mathrm{C}}_n{\mathrm{H}}_{2n+1}\mathrm{O}\mathrm{H}$.

The structure of a polymer is shown. Which statement about this polymer is correct? A Alkenes are polymerised to make the polymer. B It is a polyester. C It is an addition polymer. D Water is produced when the polymer is made.

Methane undergoes substitution reactions with chlorine and complete combustion with excess oxygen. Which row about the two reactions is correct?

What is used to identify the end-point of an acid–base titration? A balance B measuring cylinder C indicator D volumetric pipette

Four pure substances, P, Q, R and S, are tested using chromatography. The same solvent is used each time. The table shows the distance moved by each substance and by the solvent from the baseline.

Which two substances are identical? A P and R B P and S C Q and R D Q and S

A substance is tested with three different reagents. Which row shows the results obtained with aqueous iron(II) nitrate?

A student carries out a flame test on a sample. The flame colour observed is light green. Which ion is present in the sample? A ${\mathrm{B}\mathrm{a}}^{2+}$ B ${\mathrm{C}\mathrm{a}}^{2+}$ C ${\mathrm{L}\mathrm{i}}^{+}$ D ${\mathrm{K}}^{+}$