IGCSE Chemistry 0620 Paper 23, Oct/Nov 2023

A sample of a gas occupies $340{\text{ cm}}^3$ at room temperature and pressure. The temperature and pressure are both increased, but the volume occupied by the gas remains $340{\text{ cm}}^3$. Which row describes what happens to the particle speed and the average distance between the particles in the gas when the temperature and pressure are both increased?

Which statements about the rate of diffusion of the gases ammonia, carbon monoxide, nitrogen and oxygen are correct? 1 Nitrogen and carbon monoxide will diffuse at the same rate. 2 Oxygen will diffuse slowest because it is an element, whereas the others are compounds. 3 Ammonia will diffuse fastest. A 1 and 2 B 1 and 3 C 1 only D 2 and 3

The structure of an atom of element X is shown. What is element X? A boron B carbon C sodium D sulfur

Which statement explains why isotopes of an element have the same chemical reactions? A They have different numbers of neutrons. B They have ions with different numbers of electrons. C They have the same number of outer shell electrons. D They have the same number of protons.

Magnesium reacts with oxygen to form magnesium oxide. What happens to magnesium atoms and oxygen atoms during this reaction? A Magnesium and oxygen share two electrons. B Magnesium gains two electrons and oxygen loses two electrons. C Magnesium loses one electron and oxygen gains one electron. D Magnesium loses two electrons and oxygen gains two electrons.

Which row about the properties of both diamond and silicon(IV) oxide is correct?

The equation represents the reaction between solid magnesium oxide and dilute hydrochloric acid to form magnesium chloride and water. $$\text{MgO}+2\text{HCl}\to {\text{MgCl}}_2+{\text{H}}_2\text{O}$$ Which row shows the state symbols for hydrochloric acid, magnesium chloride and water?

Which substance is a mixture? A air B graphite C oxygen D water

The number of moles of atoms X, Y and Z, in a compound, are shown.

What is the formula of the compound? A ${\text{XY}}_2{\text{Z}}_4$ B ${\text{XY}}_4{\text{Z}}_2$ C ${\text{X}}_2{\text{YZ}}_4$ D ${\text{X}}_2{\text{Y}}_4\text{Z}$

$1.0\text{ mol}$ of silver nitrate, ${\text{AgNO}}_3$, contains $1.2\times {10}^{24}$ ions. How many ions are there in $0.25\text{ mol}$ of iron(III) oxide, ${\text{Fe}}_2{\text{O}}_3$? A $1.5\times {10}^{23}$ B $3.0\times {10}^{23}$ C $7.5\times {10}^{23}$ D $3.0\times {10}^{24}$

Concentrated aqueous magnesium bromide is electrolysed using carbon electrodes. Which equations represent the reactions occurring at each electrode?

Aqueous copper(II) sulfate is electrolysed using carbon electrodes. Which statement is correct? A Bubbles of hydrogen gas are formed at the anode. B Bubbles of oxygen gas are formed at the cathode. C Copper is deposited at the anode. D The blue colour of the solution fades.

When water is added to anhydrous iron(III) chloride, ${\text{FeCl}}_3$, hydrated iron(III) chloride, ${\text{FeCl}}_3\bullet 6{\text{H}}_2\text{O}$, is formed and energy is given out. $${\text{FeCl}}_3+6{\text{H}}_2\text{O}\rightleftharpoons {\text{FeCl}}_3\bullet 6{\text{H}}_2\text{O}$$ Which reaction pathway diagram represents the formation of anhydrous iron(III) chloride in the reverse reaction?

Ethene reacts with hydrogen. The equation is shown. $${\text{C}}_2{\text{H}}_4+{\text{H}}_2\to {\text{C}}_2{\text{H}}_6$$ The bond energies are shown.

What is the energy change for the reaction? A $-560\text{ kJ / mol}$ B $-124\text{ kJ / mol}$ C $+486\text{ kJ / mol}$ D $+5496\text{ kJ / mol}$

Statements about four different acids are listed. ● A $0.0100{\text{ mol / dm}}^3$ solution of hydrochloric acid has a pH of 2. ● A $0.0100{\text{ mol / dm}}^3$ solution of ethanoic acid has a pH of 3.4. ● Hydrobromic acid, HBr, is a strong acid. ● Ethanoic acid is a slightly stronger acid than trimethylethanoic acid. What are the pH values of $0.0100{\text{ mol / dm}}^3\text{ HBr}$ and $0.0100{\text{ mol / dm}}^3\text{ trimethylethanoic acid}$?

Anhydrous cobalt(II) chloride is blue and turns pink when water is added. How is this reaction reversed? A adding dilute acid B filtering C heating D cooling

The reaction between hydrogen and nitrogen is reversible. The forward reaction is exothermic. $${\text{N}}_2(\text{g})+3{\text{H}}_2(\text{g})\rightleftharpoons 2{\text{NH}}_3(\text{g})$$ Which change to the conditions would increase the yield of ammonia? A add a catalyst B increase the pressure C increase the temperature D reduce the concentration of nitrogen

Ethanol can be turned into ethanoic acid by passing it over hot copper(II) oxide. $${\text{CH}}_3{\text{CH}}_2\text{OH}+2\text{CuO}\to {\text{CH}}_3\text{COOH}+{\text{H}}_2\text{O}+2\text{Cu}$$ What is this type of reaction? A precipitation B redox C thermal decomposition D neutralisation

When heated strongly, silicon(IV) oxide reacts with carbon. $${\text{SiO}}_2+2\text{C}\to \text{Si}+2\text{CO}$$ Which term describes what happens to silicon(IV) oxide? A thermal decomposition B neutralisation C oxidation D reduction

Which statement about aqueous weak acids is correct? A Weak acids are always dilute aqueous solutions. B Weak acids dissociate fully in aqueous solution. C When a weak acid is added to blue litmus paper, it stays blue. D When a weak acid is added to solid magnesium, effervescence is seen.

Which oxides are basic? 1 calcium oxide 2 sodium oxide 3 iron(II) oxide A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 3 only

Zinc oxide is an amphoteric oxide. Zinc oxide is added to excess dilute hydrochloric acid. Zinc oxide is added to excess aqueous sodium hydroxide. Which row describes the observations made in these reactions?

Which row shows properties of an element that is in the same group of the Periodic Table as lithium?

The elements in Group VII include chlorine, bromine and iodine. Which statements are correct? 1 Iodine is more dense than chlorine. 2 Iodine displaces chlorine from a solution containing chloride ions. 3 Bromine is a diatomic non-metal. 4 Chlorine gas is darker in colour than bromine vapour. A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

Cobalt is a transition element. What is a property of cobalt? A It can form coloured compounds. B It is a poor electrical conductor. C It has a low density. D It has a low melting point.

Which metal has variable oxidation numbers? A aluminium B calcium C copper D sodium

Which statement about alloys is correct? A Alloys are pure metal elements. B At least two or more metals react together to make alloys. C Alloys can be harder and stronger than a pure metal. D Steel is not an alloy because it can contain the non-metal carbon.

A metal M is between sodium and magnesium in the reactivity series. Which reactions occur with M and its oxide?

The diagrams show experiments to investigate rusting of iron nails. In which test-tubes do the nails rust? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 1 only

Which equation represents a reaction that takes place when iron is extracted from its ore in the blast furnace? A $\text{CaO}+{\text{SiO}}_2\to {\text{CaSiO}}_3$ B $\text{CaO}+{\text{CO}}_2\to {\text{CaCO}}_3$ C $2\text{CO}\to \text{C}+{\text{CO}}_2$ D $2\text{Fe}+3{\text{CO}}_2\to {\text{Fe}}_2{\text{CO}}_3+3\text{CO}$

Some uses of water are listed. 1 for drinking 2 in chemical reactions 3 in swimming pools 4 in washing For which uses is it necessary to chlorinate the water? A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

Oxides of nitrogen are formed in car engines and are a source of air pollution. To decrease this pollution, catalytic converters are fitted to car exhausts. What happens to the oxides of nitrogen in the catalytic converter? A combustion B cracking C oxidation D reduction

Which pair of compounds are structural isomers of each other? A ${\text{CH}}_3{\text{CH}}_2{\text{CH}}_3$ and ${\text{CH}}_3{\text{CH}}_2{\text{CH}}_2{\text{CH}}_3$ B ${\text{CH}}_2={\text{CHCH}}_3$ and ${\text{CH}}_3\text{CH}={\text{CH}}_2$ C ${\text{CH}}_2(\text{OH}){\text{CH}}_2{\text{CH}}_3$ and ${\text{CH}}_3{\text{CH}}_2{\text{CH}}_2\text{OH}$ D ${\text{CH}}_3{\text{CH}}_2{\text{CH}}_2\text{COOH}$ and ${\text{CH}}_3{\text{COOCH}}_2{\text{CH}}_3$

Methane reacts with chlorine in sunlight. $${\text{CH}}_4+{\text{Cl}}_2\to {\text{CH}}_3\text{Cl}+\text{HCl}$$ Which statements about this reaction are correct? 1 It is a substitution reaction. 2 It is an addition reaction. 3 It is a photochemical reaction. 4 It is catalysed by nickel. A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

Propene reacts with bromine to give one product only. What is the formula of the product? A ${\text{CH}}_3{\text{CH}}_2{\text{CHBr}}_2$ B ${\text{CH}}_2{\text{BrCH}}_2{\text{CH}}_2\text{Br}$ C ${\text{CH}}_3{\text{CHBrCH}}_2\text{Br}$ D ${\text{CH}}_3{\text{CH}}_2{\text{CH}}_2\text{Br}$

Ethanol can be manufactured by fermentation or by the catalytic addition of steam to ethene. Which statements describe an advantage of manufacturing ethanol by fermentation? 1 The yield of ethanol is low. 2 The method uses a batch process. 3 The process takes place at a lower temperature. 4 The ethanol is made from a renewable source. A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

A compound with the formula ${\text{CH}}_3{\text{COOC}}_2{\text{H}}_5$ is formed from ethanol in two separate reactions.

Which row describes reaction 1 and reaction 2?

The flow diagram shows how poly(ethene) may be made from petroleum. $$\text{petroleum}\stackrel{1}{\to }\text{fuel oil}\stackrel{2}{\to }\text{ethene}\stackrel{3}{\to }\text{poly(ethene)}$$ What are stages 1, 2 and 3?

$R_{\text{f}}$ values are used to identify unknown substances using paper chromatography. Which statements about $R_{\text{f}}$ values are correct? 1 $R_{\text{f}}$ values are always less than 1.0. 2 $R_{\text{f}}\text{ value}=\text{distance travelled by solvent}÷\text{distance travelled by unknown substance}\mathrm{.}$ 3 The higher the $R_{\text{f}}$ value, the further the unknown substance travels. 4 $R_{\text{f}}$ values are not affected by the solubility of the unknown substance. A 1 and 2 B 1 and 3 C 2 and 3 D 3 and 4

The results of some tests on an aqueous solution of substance X are listed. 1 A cream precipitate is produced when adding aqueous silver nitrate. 2 Adding aqueous sodium hydroxide produces a green precipitate which dissolves in excess alkali. 3 Adding aqueous ammonia produces a green precipitate which is insoluble in excess ammonia. What is substance X? A chromium(III) bromide B chromium(III) chloride C iron(II) bromide D iron(II) chloride