IGCSE Chemistry 0620 Paper 21, May/June 2024

A gas is heated. The pressure is kept constant. Which statement describes the behaviour of the particles in the gas? A The particles move faster and become closer together. B The particles move faster and become further apart. C The particles move more slowly and become closer together. D The particles move more slowly and become further apart.

A mixture of ice and water is left to stand and the ice melts. Which row describes what happens as the ice is melting?

Hydrogen chloride gas [$M_r$: $\text{HCl}$, $36.5$] is released at P in the apparatus shown. The universal indicator paper turns red after $38\text{ s}$. The experiment is repeated using sulfur dioxide gas [$M_r$: ${\text{SO}}_2$, $64$]. What is the result for sulfur dioxide gas?

Four statements about atoms are listed. 1 The centre of an atom is positively charged. 2 Protons and electrons are located in the nucleus. 3 Protons and electrons have the same mass. 4 Most of the mass of an atom is in the nucleus. Which statements are correct? A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

The electronic configurations of two elements are given. element L: 2,8,8,1 element M: 2,8,4 Which row identifies the group number and the period number for element L and element M?

Which statement explains why isotopes of the same element have the same chemical properties? A They have different numbers of protons in their nucleus. B They have different numbers of neutrons in their nucleus. C They have the same electronic configuration. D They have the same number of electrons as protons.

Which statements about potassium chloride are correct? 1 It conducts electricity when solid because its ions are free to move. 2 It has a high melting point because it has strong intermolecular forces. 3 Its structure is a giant lattice of alternating positive and negative ions. 4 It is soluble in water. A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

How many electrons are shared in one molecule of nitrogen and in one molecule of ethene?

What is the total number of electrons in one molecule of ammonia, ${\text{NH}}_3$? A 6 B 8 C 10 D 11

When heated, copper(II) oxide, $\text{CuO}$, reacts with ammonia, ${\text{NH}}_3$. $$3\text{CuO}+2{\text{NH}}_3\to 3\text{Cu}+{\text{N}}_2+3{\text{H}}_2\text{O}$$ $8.5\text{ g}$ of ammonia reacts with an excess of copper(II) oxide to produce $26.4\text{ g}$ of copper. What is the percentage yield of copper in this reaction? A 27.5% B 32.2% C 55.0% D 82.5%

What is the empirical formula of ethanoic acid? A $\text{CHO}$ B ${\text{CH}}_2\text{O}$ C ${\text{C}}_2{\text{H}}_2\text{O}$ D ${\text{C}}_2{\text{H}}_4{\text{O}}_2$

Magnesium chloride, ${\text{MgCl}}_2$, contains magnesium ions and chloride ions. How many chloride ions are present in two moles of magnesium chloride? A $6.02\times {10}^{23}$ B $1.204\times {10}^{24}$ C $2.408\times {10}^{24}$ D $3.612\times {10}^{24}$

A metal object is electroplated with copper. One electrode is the metal object and the other electrode is copper. The electrolyte is aqueous copper(II) sulfate. Which row shows the ionic half-equation for the reaction at the anode and the observation of the electrolyte?

Which statement about electrolysis is correct? A Chemical energy is converted to electrical energy. B Electrons flow through the electrolyte. C Ionic compounds are broken down. D Metals are formed at the positive electrode.

The reaction between hydrogen and oxygen releases $486\text{ kJ / mol}$ of energy. $$2{\text{H}}_2(\text{g})+{\text{O}}_2(\text{g})\to 2{\text{H}}_2\text{O}(\text{g})$$ The bond energy of $\text{H–H}$ is $436\text{ kJ / mol}$ and that of $\text{H–O}$ is $464\text{ kJ / mol}$. What is the bond energy of $\text{O=O}$? A $430\text{ kJ / mol}$ B $458\text{ kJ / mol}$ C $498\text{ kJ / mol}$ D $984\text{ kJ / mol}$

Which reaction pathway diagram shows the reaction that will give out the most energy? The scale on the y-axis is the same in each diagram.

When calcium carbonate is heated strongly, a gas is given off. Which word describes this change? A chemical B exothermic C physical D reduction

Powdered magnesium carbonate is added to excess dilute hydrochloric acid. The total volume of gas produced is measured over time. A graph of the results is shown. The experiment is repeated but the concentration of the hydrochloric acid is doubled. All other conditions are kept the same. Which statements about the second experiment are correct? 1 The final volume of gas is $360{\text{ cm}}^3$. 2 The reaction finishes before 90 seconds. 3 The activation energy of the reaction is lower. A 1 and 2 B 1 and 3 C 2 and 3 D 2 only

Which statements explain why increasing the temperature changes the rate of a chemical reaction? 1 It increases the activation energy. 2 It increases the frequency of collisions between the reacting particles. 3 It increases the kinetic energy of the reacting particles. 4 It increases the number of particles per unit volume. A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

Hydrogen is made by reacting carbon with steam. The equation for the reaction is shown. $$\text{C(s)}+{\text{H}}_2\text{O(g)}\rightleftharpoons {\text{H}}_2\text{(g)}+\text{CO(g)}$$ The forward reaction is endothermic. Which row describes changes in the pressure and the temperature that will both shift the position of equilibrium to the right?

Which row shows the conditions used for the conversion of sulfur dioxide to sulfur trioxide in the Contact process?

The equation for the reaction of magnesium with carbon dioxide is shown. $$2\text{Mg}+{\text{CO}}_2\to 2\text{MgO}+\text{C}$$ Which statement about this reaction is correct? A Magnesium is oxidised and carbon dioxide is reduced. B Magnesium is reduced and carbon dioxide is oxidised. C Magnesium and carbon dioxide are both oxidised. D Magnesium and carbon dioxide are neither oxidised nor reduced.

Chlorine displaces bromine from aqueous potassium bromide. The ionic equation for the reaction is shown. $${\text{Cl}}_2+2{\text{Br}}^{-}\to 2{\text{Cl}}^{-}+{\text{Br}}_2$$ Which statement about this reaction is correct? A Bromide ions act as an oxidising agent. B Bromide ions are oxidised as electrons are lost. C Chlorine acts as a reducing agent. D Chlorine is reduced as electrons are lost.

Which gas is produced when ammonium chloride is warmed with aqueous sodium hydroxide? A ammonia B chlorine C hydrogen D nitrogen

Which equation represents a solution of ethanoic acid in water? A $\text{HCOOH(aq)}\rightleftharpoons {\text{HCOO}}^{-}\text{(aq)}+{\text{H}}^{+}\text{(aq)}$ B $\text{HCOOH(aq)}\to {\text{HCOO}}^{-}\text{(aq)}+{\text{H}}^{+}\text{(aq)}$ C ${\text{CH}}_3\text{COOH(aq)}\rightleftharpoons {\text{CH}}_3{\text{COO}}^{-}\text{(aq)}+{\text{H}}^{+}\text{(aq)}$ D ${\text{CH}}_3\text{COOH(aq)}\to {\text{CH}}_3{\text{COO}}^{-}\text{(aq)}+{\text{H}}^{+}\text{(aq)}$

Four statements about the reactions of oxides with dilute hydrochloric acid and with aqueous sodium hydroxide are listed. 1 Aluminium oxide reacts with both dilute hydrochloric acid and aqueous sodium hydroxide. 2 Calcium oxide reacts with both dilute hydrochloric acid and aqueous sodium hydroxide. 3 Copper(II) oxide reacts with dilute hydrochloric acid but not with aqueous sodium hydroxide. 4 Sulfur dioxide does not react with either dilute hydrochloric acid or aqueous sodium hydroxide. Which statements are correct? A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

Which statement about elements in Period 3 of the Periodic Table is correct? A Aluminium is a non-metal in Group III. B Argon is in Group VIII and has eight electrons in its outer electron shell. C Magnesium is in Group II and has three electrons in its outer electron shell. D Sulfur is a metal in Group VI.

Which row describes the structure of Group VII elements and the trend in their reactivity down the group?

Some information about four elements, P, Q, R and S, is shown.

Which elements are transition elements? A P and R B P and S C Q and R D R and S

Propanoic acid is a carboxylic acid. It has similar chemical properties to ethanoic acid. Which statements are correct? 1 Aqueous propanoic acid is a weaker acid than dilute hydrochloric acid. 2 Propanoic acid partially ionises in aqueous solution. 3 Propanoic acid reacts with ethanol to form propyl ethanoate. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Iron rusts in the presence of oxygen and water. Which statements about the rusting of iron are correct? 1 Anhydrous iron(II) oxide is produced when iron rusts. 2 Iron rusts more quickly when attached to a piece of zinc. 3 Coating the iron with plastic prevents the iron from rusting. 4 Iron loses electrons when it rusts. A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

An iron nail is added to aqueous copper(II) sulfate and a different iron nail is added to aqueous magnesium sulfate. The results are shown.

Which statement is correct? A Copper atoms are oxidised more easily than magnesium atoms. B Copper atoms are reduced more easily than iron ions. C Iron atoms are oxidised more easily than copper atoms. D Iron atoms are reduced more easily than copper ions.

Which pollutant leads to the deoxygenation of water in ponds and lakes? A fertilisers containing nitrates and phosphates B toxic metal compounds C combustion products of fossil fuels D acid rain

Which statement identifies a sample of water as pure? A It melts at room temperature. B It turns anhydrous copper(II) sulfate blue. C It turns hydrated cobalt(II) chloride from blue to pink. D It boils at 100 °C.

Oxides of nitrogen are produced by car engines. In a catalytic converter oxides of nitrogen are removed by reacting them with compound X. Which row describes the type of reaction oxides of nitrogen undergo and identifies compound X?

What is a disadvantage of producing ethanol using the catalytic addition of steam to ethene? A the energy cost is low B the process is continuous C the process uses a non-renewable raw material D the ethanol is pure

Which statement about the polymer PET is correct? A It can be broken down into its monomers and re-polymerised. B It is an addition polymer. C It is a polyamide. D It is made from amino acid monomers.

The formulae of five compounds are listed. 1 ${\text{C}}_4{\text{H}}_{10}$ 2 ${\text{C}}_2{\text{H}}_5\text{OH}$ 3 ${\text{C}}_4{\text{H}}_9\text{OH}$ 4 ${\text{C}}_4{\text{H}}_9\text{COOH}$ 5 ${\text{C}}_5{\text{H}}_{11}\text{OH}$ Which compounds are in the same homologous series? A 1, 3 and 4 B 2, 3 and 5 C 3 and 4 only D 3 and 5 only

Propane reacts with chlorine. Which statements about this reaction are correct? 1 Ultraviolet light is used to provide the activation energy. 2 Propane undergoes an addition reaction. 3 One of the products is ${\text{CH}}_3{\text{CH}}_2\text{Cl}$. 4 One of the products is $\text{HCl}$. A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

Which statement about chromatography is correct? A It is not possible for two different substances to have the same $R_f$ value. B It is only possible to use chromatography on substances which have a colour. C It is possible to use chromatography on colourless substances using a locating agent. D $\text{The }{R}_f\text{ value of a substance}=\frac{\text{the distance travelled by the solvent}}{\text{the distance travelled by the substance}}$