IGCSE Chemistry 0620 Paper 21, May/June 2026

When water evaporates from a brass surface, the temperature of the brass surface decreases. Which row describes this evaporation process?

A solid lump of tin is heated until it melts. Which statements describe what happens when solid tin melts? 1 The atoms of tin move further apart. 2 The atoms of tin lose thermal energy to the surroundings. 3 The atoms of tin gain thermal energy from the surroundings. 4 The temperature of the tin increases. A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

A gas is placed in a sealed container. The gas has a pressure of one atmosphere and a temperature of $50{}^{\circ }\text{C}$. It is then heated to $100{}^{\circ }\text{C}$. Which row describes the cause of the pressure of the gas and the effect of increasing the temperature of the gas?

A sample of element $\text{X}$ has two isotopes. The symbols for the two isotopes are ${}^{63}\text{X}$ and ${}^{65}\text{X}$. The relative abundance of ${}^{65}\text{X}$ is $25.0\mathrm{\%}$. What is the relative atomic mass of $\text{X}$? A 63.5 B 63.7 C 64.0 D 64.5

Which statement about magnesium chloride, ${\text{MgCl}}_2$, is correct? A Molten magnesium chloride conducts electricity because its electrons are free to move. B It consists of anions and cations which have completely filled outer electron shells. C It has a high melting point because its covalent bonds are very strong. D The magnesium ions and chloride ions are bonded together by delocalised electrons.

Which row describes the structure of a solid metal and explains the property?

Which atom or ion has the electronic configuration $2,8,8$? A $\text{Ne}$ B ${\text{Na}}^{+}$ C ${\text{Br}}^{-}$ D ${\text{Ca}}^{2+}$

The formula of a compound containing element $\text{Z}$ is ${\text{Na}}_2{\text{Z}}_2{\text{O}}_3$. The relative formula mass of the compound is $158$. What is the relative atomic mass of $\text{Z}$? A 32 B 59.5 C 64 D 119

Magnesium reacts with steam to form hydrogen. $$\text{Mg}+{\text{H}}_2\text{O}\to \text{MgO}+{\text{H}}_2$$ How many molecules of hydrogen gas are made when $3.6\text{ g}$ of magnesium are heated with $1.8\text{ g}$ of steam? (Assume Avogadro's constant $=6\times {10}^{23}$ and the yield of magnesium oxide is $100\mathrm{\%}$.) A $6\times {10}^{22}$ B $12\times {10}^{22}$ C $9\times {10}^{22}$ D $18\times {10}^{22}$

Compound $\text{Y}$ contains $48.65\mathrm{\%}$ carbon, $8.10\mathrm{\%}$ hydrogen and $43.25\mathrm{\%}$ oxygen by mass. What is the empirical formula of compound $\text{Y}$? A ${\text{C}}_3{\text{H}}_3{\text{O}}_2$ B ${\text{C}}_2{\text{H}}_3\text{O}$ C ${\text{CH}}_3\text{O}$ D ${\text{C}}_3{\text{H}}_6{\text{O}}_2$

Calcium carbonate is reacted with an excess of dilute hydrochloric acid. $${\text{CaCO}}_3+2\text{HCl}\to {\text{CaCl}}_2+{\text{H}}_2\text{O}+{\text{CO}}_2$$ Which two changes, when applied together, will increase both the rate of reaction and the volume of carbon dioxide produced? A increasing the concentration of hydrochloric acid and adding a catalyst B increasing the volume of hydrochloric acid and the temperature of the reaction C increasing the mass of calcium carbonate and the temperature of the reaction D increasing the surface area of the calcium carbonate and adding a catalyst

Concentrated aqueous sodium chloride and dilute sulfuric acid are electrolysed with inert electrodes. Which row describes the electrode products for each electrolyte?

Which diagram shows the direction of movement of ions and electrons during the electrolysis of molten sodium chloride?

Which statement about hydrogen fuel cells is correct? A Hydrogen fuel cells produce water as the only product. B Hydrogen fuel cells do not need oxygen. C The waste from a hydrogen fuel cell is an acidic gas. D The reaction in a fuel cell is endothermic.

Which equation represents an endothermic reaction? A ${\text{CH}}_4\text{(g)}+2{\text{O}}_2\text{(g)}\to {\text{CO}}_2\text{(g)}+2{\text{H}}_2\text{O(l)}$ B ${\text{Cl}}_2\text{(g)}\to 2\text{Cl(g)}$ C $\text{H(g)}+\text{H(g)}\to {\text{H}}_2\text{(g)}$ D $2\text{K(s)}+2{\text{H}}_2\text{O(l)}\to 2\text{KOH(aq)}+{\text{H}}_2\text{(g)}$

The diagram shows the reaction pathway diagram for the reaction between $\text{X}$ and $\text{Y}$ to form product $\text{Z}$. The reaction happens more rapidly if a catalyst is used. How would the diagram change when a catalyst is used? A The arrow representing $E_{\text{a}}$ would be larger. B The arrow representing $E_{\text{a}}$ would be smaller. C The arrow representing $\mathrm{\Delta }H$ would be larger. D The arrow representing $\mathrm{\Delta }H$ would be smaller.

In a reaction, element $\text{J}$ acts as an oxidising agent. Which statements about $\text{J}$ are correct? 1 $\text{J}$ is oxidised. 2 $\text{J}$ gains electrons. 3 $\text{J}$ loses electrons. 4 The oxidation number of $\text{J}$ decreases. A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

Four statements about the Haber process and the Contact process are listed. 1 Both processes are carried out at $200\text{ kPa}$. 2 Both processes are carried out at $450{}^{\circ }\text{C}$. 3 Both processes use a reactant that is extracted from air. 4 Both processes use iron as a catalyst. Which two statements are correct? A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

Sodium hydroxide forms an alkaline solution. Which indicator turns yellow when added to this solution? A litmus B methyl orange C thymolphthalein D universal indicator

What is the definition of a strong acid? A It is a proton acceptor that is completely dissociated in aqueous solution. B It is a proton acceptor that is partially dissociated in aqueous solution. C It is a proton donor that is completely dissociated in aqueous solution. D It is a proton donor that is partially dissociated in aqueous solution.

Tin(II) oxide, $\text{SnO}$, is amphoteric. Which reactions show that tin(II) oxide is amphoteric? 1 $4\text{SnO}\to 2{\text{SnO}}_2+2\text{Sn}$ 2 $\text{SnO}+2\text{HCl}\to {\text{SnCl}}_2+{\text{H}}_2\text{O}$ 3 $2\text{SnO}+{\text{O}}_2\to 2{\text{SnO}}_2$ 4 $\text{SnO}+2\text{NaOH}\to {\text{Na}}_2{\text{SnO}}_2+{\text{H}}_2\text{O}$ A 1 and 2 B 1 and 3 C 2 and 3 D 2 and 4

Which statement defines the term water of crystallisation? A the water molecules removed from a solution when a crystalline substance is formed B the water required to dissolve a crystalline substance to make a solution C the water molecules present in a hydrated crystalline solid D the water added to a hydrated crystallised solid to make it anhydrous

The diagram shows the melting points of some Group I elements. What is the melting point of potassium? A $185.5{}^{\circ }\text{C}$ B $120.0{}^{\circ }\text{C}$ C $63.5{}^{\circ }\text{C}$ D $30.0{}^{\circ }\text{C}$

Which row about the similarities and differences between chlorine and bromine is correct?

Which property of a metal is necessary for the named use?

The equation for the reaction between magnesium and aqueous copper(II) sulfate is shown. $$\text{Mg}+{\text{CuSO}}_4\to \text{Cu}+{\text{MgSO}}_4$$ Which statement is correct? A Copper ions are oxidised to copper metal during the reaction. B Copper is displaced because it is more reactive than magnesium. C The oxidation number of magnesium decreases during the reaction. D The reaction happens because magnesium has a greater tendency to form positive ions than copper.

Steel is an alloy of iron. Zinc is used to protect a steel car body from rusting. The steel body is completely coated in zinc. Which statements about this use of zinc are correct? 1 The layer of zinc prevents oxygen reaching the steel to cause rust. 2 Zinc is used because it is a more reactive metal than iron. 3 If the zinc layer is scratched, the steel will rust. A 1, 2 and 3 B 1 and 2 only C 1 only D 2 and 3 only

Which test results show that a sample of water is pure? 1 Its boiling point is $100{}^{\circ }\text{C}$. 2 Its freezing point is $0{}^{\circ }\text{C}$. 3 It turns anhydrous cobalt(II) chloride from blue to pink. 4 It turns anhydrous copper(II) sulfate from white to blue. A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

Which mixture of salts can be used as an NPK fertiliser? A ammonium phosphate + potassium sulfate B calcium phosphate + sodium nitrate C potassium nitrate + calcium sulfate D sodium phosphate + ammonium nitrate

Three air pollutants, $\text{X}$, $\text{Y}$ and $\text{Z}$, are described. $\text{X}$ is a toxic gas formed by the incomplete combustion of fossil fuels. $\text{Y}$ is formed by decomposing vegetation and increases global warming. $\text{Z}$ is a cause of breathing problems and acid rain. What are $\text{X}$, $\text{Y}$ and $\text{Z}$?

Which statement about members of the carboxylic acid homologous series is correct? A They have the same empirical formula and similar chemical properties. B They have the same empirical formula and their displayed formula differs by a $-{\text{CH}}_2-$ unit. C They have the same functional group and the same physical properties. D They have the same functional group and similar chemical properties.

Which of the named compounds have the correct structural formula? 1 ethanoic acid, ${\text{CH}}_3{\text{CH}}_2\text{COOH}$ 2 propan-2-ol, ${\text{CH}}_3{\text{CH(OH)CH}}_3$ 3 but-2-ene, ${\text{CH}}_3{\text{CH=CHCH}}_3$ A 1 and 2 B 1 and 3 C 2 and 3 D 3 only

The diagram shows a simple fractionating column for petroleum. Which outlet produces the fraction with the most viscous liquids?

Propene reacts separately with: • liquid bromine, ${\text{Br}}_2$ • hydrogen gas, ${\text{H}}_2$ • steam, ${\text{H}}_2\text{O}$. Which statement about these three reactions is correct? A Two of the reactions are addition reactions and one is a substitution reaction. B The products of all three of these reactions are molecules containing exactly 9 atoms. C The products of two of these reactions are molecules containing exactly 9 atoms. D The products of two of these reactions are molecules containing exactly 11 atoms.

Polymers are described as addition polymers or condensation polymers. Which two rows give a correct statement about each type of polymerisation?

A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

Alanine is an amino acid. The structural formula of alanine is shown. It is the only monomer in a polymer. Which diagram represents a section of this polymer?

Which statements describe an environmental challenge caused by the disposal of plastics? 1 The burning of the plastics can release toxic gases. 2 Plastics are harmful to marine life. 3 Plastics decompose very slowly in the environment. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Magnesium reacts with dilute hydrochloric acid to produce hydrogen gas. Which pieces of apparatus are needed to determine the rate of this reaction? A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

Solution $\text{X}$ contains aqueous sulfite ions. Which method describes the test for the aqueous sulfite ions in $\text{X}$? A Add nitric acid to $\text{X}$. The gas produced turns limewater cloudy. B Add nitric acid to $\text{X}$. The gas produced decolourises aqueous potassium manganate(VII). C Add nitric acid to $\text{X}$ then add aqueous barium chloride to give a white precipitate. D Add nitric acid to $\text{X}$ then add aqueous silver nitrate to give a pale yellow precipitate.

A chemical mixture is separated using paper chromatography. The chromatogram is shown. Which statements are correct? 1 The spot nearest the solvent front has an $R_{\text{f}}$ value greater than $0.50$. 2 Insoluble compounds rise with the solvent front. 3 The lower spot is a less soluble substance than the higher spot. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only