IGCSE Chemistry 0620 Paper 22, May/June 2025

An ice cube melts. ice cube $\to$ pool of water What happens to the molecules of water in the ice cube? A They evaporate. B They dissolve. C They gain energy. D They lose energy.

A sample of a liquid, X, is heated to a temperature above its boiling point. X is then cooled, so that it condenses and then freezes. Which graph describes the change in temperature of X over time?

Which row gives the number of protons, electrons and neutrons in an atom of zinc?

Which particles have the electronic configuration 2,8,8? 1 an argon atom, $\text{Ar}$ 2 an aluminium ion, ${\text{Al}}^{3+}$ 3 a sodium ion, ${\text{Na}}^{+}$ 4 a chloride ion, ${\text{Cl}}^{-}$ A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

A sample of element Q has two isotopes. Their relative masses and abundances are shown.

What is the relative atomic mass of this sample of Q to three significant figures? A 240 B 241 C 242 D 243

Which statement about silicon(IV) oxide, ${\text{SiO}}_2$, is correct? A It conducts electricity because it contains delocalised electrons. B It has a giant covalent structure with each silicon atom bonded to four oxygen atoms. C It is a simple covalent molecule. D Its structure is similar to that of graphite.

When $65\text{ g}$ of zinc reacts with $32\text{ g}$ of sulfur, $97\text{ g}$ of zinc sulfide is produced. When $65\text{ g}$ of zinc reacts with $40\text{ g}$ of sulfur, the mass of zinc sulfide produced is still $97\text{ g}$. Which statement explains this observation? A Some of the zinc sulfide evaporates. B The reaction rate is slow. C The reaction stops before it is complete. D Zinc is the limiting reactant.

Aluminium reacts with iron(III) oxide to form aluminium oxide and iron. Which chemical equation for the reaction between aluminium and iron(III) oxide is correct? A $\text{Al}+\text{FeO}\to \text{AlO}+\text{Fe}$ B $2\text{Al}+{\text{Fe}}_2\text{O}\to {\text{Al}}_2\text{O}+2\text{Fe}$ C $\text{Al}+{\text{Fe}}_2{\text{O}}_3\to {\text{Al}}_2{\text{O}}_3+\text{Fe}$ D $2\text{Al}+{\text{Fe}}_2{\text{O}}_3\to {\text{Al}}_2{\text{O}}_3+2\text{Fe}$

The concentration of a solution of aqueous sodium hydroxide is $0.50\text{ mol}\mathrm{/}{\text{dm}}^3$. Which mass of sodium hydroxide is used to make $500{\text{ cm}}^3$ of this solution? A $10\text{ g}$ B $20\text{ g}$ C $40\text{ g}$ D $160\text{ g}$

Molten zinc oxide is electrolysed using inert electrodes. Which row identifies the product at each electrode?

Dilute aqueous sodium chloride is electrolysed using platinum electrodes. What is the half-equation for the reaction at the cathode? A $2{\text{H}}^{+}+2{\text{e}}^{-}\to {\text{H}}_2$ B ${\text{Na}}^{+}+{\text{e}}^{-}\to \text{Na}$ C $2{\text{Cl}}^{-}\to {\text{Cl}}_2+2{\text{e}}^{-}$ D $4{\text{OH}}^{-}\to 2{\text{H}}_2\text{O}+{\text{O}}_2+4{\text{e}}^{-}$

Hydrogen–oxygen fuel cells can be used to power vehicles. Which statement about hydrogen–oxygen fuel cells is correct? A The equation for the overall reaction is ${\text{H}}_2+{\text{O}}_2\to {\text{H}}_2{\text{O}}_2$. B The only chemical products are water and carbon dioxide. C Chemical energy in the fuel is converted into electrical energy. D The hydrogen used in hydrogen–oxygen fuel cells is a fossil fuel.

A reaction pathway diagram is shown. Which row identifies the type of reaction and how the temperature of the surroundings changes during the reaction?

The average bond energy for the $\text{C–H}$ bond is $413\text{ kJ}\mathrm{/}\text{mol}$. What is the enthalpy change when $1.0\text{ mol}$ of methane molecules is formed from carbon and hydrogen atoms? A $-1652\text{ kJ}$ B $-413\text{ kJ}$ C $+413\text{ kJ}$ D $+1652\text{ kJ}$

Which statement describes the effect of adding a catalyst to a chemical reaction? A The activation energy, $E_a$, of the reaction is increased. B The enthalpy change, $\mathrm{\Delta }H$, of the reaction stays unchanged. C The frequency of collisions between the particles is decreased. D The kinetic energy of the particles is increased.

Which row describes the conditions used in the manufacture of sulfuric acid by the Contact process?

Which equations show the underlined species acting as a reducing agent? 1 ${\text{Fe}}_2{\text{O}}_3+\underset{‾}{3\text{CO}}\to 2\text{Fe}+3{\text{CO}}_2$ 2 $\underset{‾}{\text{Fe}}+{\text{CuSO}}_4\to {\text{FeSO}}_4+\text{Cu}$ 3 $\underset{‾}{5{\text{Fe}}^{2+}}+{\text{MnO}}_4^{-}+8{\text{H}}^{+}\to 5{\text{Fe}}^{3+}+{\text{Mn}}^{2+}+4{\text{H}}_2\text{O}$ 4 $\underset{‾}{{\text{Fe(OH)}}_2}+{\text{H}}_2{\text{SO}}_4\to {\text{FeSO}}_4+2{\text{H}}_2\text{O}$ A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

A farmer incorrectly adds two substances to the soil at the same time. They react together to form a gas which turns damp red litmus paper blue. What are the two substances? A a basic oxide and a potassium salt B a basic oxide and an ammonium salt C an acidic oxide and a potassium salt D an acidic oxide and an ammonium salt

Which row shows the equations for the dissociation of hydrochloric acid and of ethanoic acid in aqueous solution?

Which three oxides are all acidic? A $\text{CaO}$, ${\text{NO}}_2$, ${\text{SO}}_2$ B $\text{CaO}$, ${\text{CO}}_2$, ${\text{Na}}_2\text{O}$ C ${\text{CO}}_2$, ${\text{NO}}_2$, ${\text{SO}}_2$ D ${\text{CO}}_2$, ${\text{Na}}_2\text{O}$, ${\text{SO}}_2$

The table shows some properties of noble gases.

Which row predicts the density and the boiling point of krypton?

Sodium is a Group I metal. What is a physical property of sodium? A non-conductor of electricity B high melting point C high density D malleable

Tennessine (atomic number 117) is a manufactured element that is below astatine in Group VII of the Periodic Table. What is the expected state of tennessine at room temperature and pressure? A a diatomic gas B a liquid C a monatomic gas D a solid

When chlorine is bubbled into aqueous sodium bromide, a displacement reaction occurs. Which description of this reaction is correct? A Chloride displaces bromide. B Chlorine displaces bromine. C Chloride displaces bromine. D Chlorine displaces bromide.

Brass is an alloy of copper. Which statement about brass or copper is correct? A Brass does not conduct electricity because it is a compound. B Copper conducts electricity because its atoms are free to move. C Brass is harder than copper because its layers of atoms cannot easily slide over each other. D Copper is stronger than brass because it is a pure metal.

The ionic equations for some reactions between metals and aqueous metal ions are shown. $$\text{Cu}+2{\text{Ag}}^{+}\to 2\text{Ag}+{\text{Cu}}^{2+}$$ $$\text{Mg}+{\text{Zn}}^{2+}\to {\text{Mg}}^{2+}+\text{Zn}$$ $$\text{Zn}+{\text{Cu}}^{2+}\to \text{Cu}+{\text{Zn}}^{2+}$$ $$\text{Sn}+{\text{Cu}}^{2+}\to {\text{Sn}}^{2+}+\text{Cu}$$ Which further information can be used to place copper, magnesium, silver, tin and zinc in order of their reactivity? A Zinc reacts with ${\text{Sn}}^{2+}$ ions. B Copper does not react with ${\text{Sn}}^{2+}$ ions. C Magnesium reacts with ${\text{Cu}}^{2+}$ ions. D Magnesium reacts with ${\text{Ag}}^{+}$ ions.

Zinc is used to galvanise iron to prevent it from rusting. Which statements are correct? 1 Galvanising is an example of a barrier method. 2 If the zinc is scratched, the iron will rust very quickly. 3 Galvanising is an example of sacrificial protection. 4 Zinc is more reactive than iron and so accepts electrons more readily. A 1, 2 and 4 B 1 and 3 C 2, 3 and 4 D 2 and 3 only

Which equation represents a reaction that occurs in a blast furnace during the extraction of iron from hematite? A $\text{Ca}+{\text{CO}}_2\to \text{CaO}+\text{CO}$ B ${\text{Fe}}_2{\text{O}}_3+3\text{Ca}\to 2\text{Fe}+3\text{CaO}$ C ${\text{Ca(OH)}}_2\to \text{CaO}+{\text{H}}_2\text{O}$ D ${\text{Fe}}_2{\text{O}}_3+3\text{CO}\to 2\text{Fe}+3{\text{CO}}_2$

Water is added separately to anhydrous copper(II) sulfate and to anhydrous cobalt(II) chloride. Which row shows the colour changes?

Gases which cause acid rain form in car engines. These gases can be removed using a catalytic converter. Which equation represents the removal of one of these gases using a catalytic converter? A ${\text{CO}}_2+\text{C}\to 2\text{CO}$ B $2\text{CO}+2\text{NO}\to 2{\text{CO}}_2+{\text{N}}_2$ C ${\text{N}}_2+2{\text{O}}_2\to 2{\text{NO}}_2$ D $2\text{NO}+{\text{O}}_2\to 2{\text{NO}}_2$

Which statements about carbon dioxide are correct? 1 Carbon dioxide absorbs thermal energy from the Earth. 2 Carbon dioxide increases the thermal energy loss to space. 3 The level of carbon dioxide in the atmosphere has increased due to the burning of fossil fuels. 4 Carbon dioxide is the only gas that causes global warming. A 1 and 2 B 1 and 3 C 2 and 3 D 2 and 4

What is the structural formula of butan-2-ol? A ${\text{CH}}_3{\text{CH}}_2{\text{CH}}_2\text{OH}$ B ${\text{CH}}_3{\text{CH(OH)CH}}_3$ C ${\text{CH}}_3{\text{CH}}_2{\text{CH}}_2{\text{CH}}_2\text{OH}$ D ${\text{CH}}_3{\text{CH}}_2{\text{CH(OH)CH}}_3$

Methanol reacts with ethanoic acid to form an ester. What is the displayed formula for this ester?

Petroleum can be separated into useful fractions by fractional distillation. Which row shows a correct use of the named fraction?

Ethane reacts with chlorine in the presence of ultraviolet light. Which products are formed? A ${\text{ClCH}}_2{\text{CH}}_2\text{Cl}$ and ${\text{H}}_2$ B $2{\text{CH}}_3\text{Cl}$ and ${\text{H}}_2$ C ${\text{C}}_2{\text{H}}_5\text{Cl}$ and $\text{HCl}$ D ${\text{CH}}_2={\text{CH}}_2$ and $2\text{HCl}$

Ethanol can be made by the fermentation of aqueous glucose and by the catalytic addition of steam to ethene. What are two advantages of making ethanol by the catalytic addition of steam to ethene rather than by the fermentation of aqueous glucose? A faster reaction and renewable raw materials B purer product and faster reaction C renewable raw materials and continuous process D uses more energy and forms a purer product

The structure of a polymer repeat unit is shown. Which pair of monomers is used to make this polymer?

Which item of apparatus is used to measure exactly $26.3{\text{ cm}}^3$ of a liquid?

A mixture containing an aqueous salt and an insoluble salt is filtered. Which row describes X and Y?

Pure ethanol has a melting point of $-114{}^{\circ }\text{C}$ and a boiling point of $78{}^{\circ }\text{C}$. What are the melting and boiling points of a sample of ethanol with glucose dissolved in it?