IGCSE Chemistry 0620 Paper 21, Oct/Nov 2024

Which row describes the arrangement and motion of the particles in a liquid?

Which gas has the lowest rate of diffusion at room temperature and pressure? A the gas produced when ammonium chloride is heated with aqueous sodium hydroxide B the gas which makes up approximately 78% of clean, dry air C the gas produced when sodium carbonate is added to dilute hydrochloric acid D the gas produced when zinc is added to dilute sulfuric acid

Which diagram represents one helium atom? A B C D

The diagram shows part of an ionic lattice structure. Which compound does the diagram represent? A potassium bromide B sodium oxide C magnesium chloride D carbon monoxide

Which statement about nitrogen molecules and ethene molecules is correct? A A nitrogen molecule has 2 more shared electrons than an ethene molecule. B An ethene molecule has 3 more shared electrons than a nitrogen molecule. C A nitrogen molecule has 4 more shared electrons than an ethene molecule. D An ethene molecule has 6 more shared electrons than a nitrogen molecule.

Sulfur is a simple molecule with the formula ${\text{S}}_8$. Which row describes and explains the melting point of sulfur?

Which row identifies a property and an explanation of the property for both diamond and silicon(IV) oxide?

Which statement about the structure of metals explains why metals are malleable? A The electrons can move freely throughout the lattice. B The layers of metal ions can slide over each other. C The metal ions are positively charged. D There is a strong force of attraction between the metal ions and the electrons.

What is the formula of iron(III) oxide? A $\text{FeO}$ B ${\text{Fe}}_3{\text{O}}_4$ C ${\text{FeO}}_2$ D ${\text{Fe}}_2{\text{O}}_3$

Calcium carbonate is heated. Calcium oxide and carbon dioxide gas are formed. The equation for the reaction is shown. $${\text{CaCO}}_3\to \text{CaO}+{\text{CO}}_2$$ $225\text{ kg}$ of calcium carbonate is heated until there is no further change in mass. The yield of calcium oxide is $85\text{ kg}$. What is the percentage yield? A $37.8\mathrm{\%}$ B $47.2\mathrm{\%}$ C $67.5\mathrm{\%}$ D $85.0\mathrm{\%}$

The apparatus used for electrolysis is shown. Which statement is correct? A Copper forms at the anode in some electrolysis reactions. B Hydrogen forms at the cathode in some electrolysis reactions. C Oxygen forms at the cathode in some electrolysis reactions. D Sodium forms at the anode in some electrolysis reactions.

Which statement about the electrolysis of aqueous copper(II) sulfate is correct? A When copper electrodes are used, the solution turns from blue to colourless. B When graphite electrodes are used, bubbles of gas are formed at the cathode. C When copper electrodes are used, the anode gets smaller. D When graphite electrodes are used, the colour of the solution does not change.

Which statement describes an advantage of using a hydrogen–oxygen fuel cell in a car compared to a gasoline engine? A The hydrogen is difficult to store. B The hydrogen is highly flammable. C The hydrogen used is made from hydrocarbons. D The only chemical product is water.

Two reaction pathway diagrams are shown. Which arrow represents the activation energy for a reaction which releases thermal energy? A B C D

Which statements about the Haber process are correct? 1 A high temperature is used because the reaction is slow at room temperature. 2 A high pressure is used because there are more moles of gaseous reactants than moles of gaseous product. 3 A nickel catalyst is used to increase the rate of reaction. 4 An iron catalyst is used to increase the equilibrium yield of ammonia. A 1 and 2 B 1 and 4 C 2 and 3 D 4 only

Which substance is a raw material used to manufacture sulfuric acid? A vanadium(V) oxide B sulfur C sulfur dioxide D sulfur trioxide

Which colours are seen when litmus and methyl orange are added to separate samples of aqueous sodium hydroxide?

Information about the solubility in water of four oxides is shown. Which oxide, when added to water, gives a solution with a pH less than pH 7?

Copper(II) sulfate is made when copper(II) carbonate reacts with dilute sulfuric acid. $${\text{CuCO}}_3+{\text{H}}_2{\text{SO}}_4\to {\text{CuSO}}_4+{\text{H}}_2\text{O}+{\text{CO}}_2$$ Pure copper(II) sulfate crystals are obtained. Which reagent is in excess and how are the crystals obtained?

Which statement about elements in Group I or Group VII of the Periodic Table is correct? A Bromine reacts with potassium chloride to produce chlorine. B Iodine is a monatomic non-metal. C Lithium has a higher melting point than potassium. D Sodium is more reactive with water than potassium.

Some information about an element from Group VII of the Periodic Table is shown.

What is the element? A fluorine B chlorine C bromine D iodine

Manganese(IV) oxide, ${\text{MnO}}_2$, is a black solid. The equation for the reaction between manganese(IV) oxide and dilute hydrochloric acid is shown. $${\text{MnO}}_2+4\text{HCl}\to {\text{MnCl}}_2+2{\text{H}}_2\text{O}+{\text{Cl}}_2$$ The reaction produces a pale pink solution. Which properties of transition elements does this reaction show? 1 They can act as catalysts. 2 They form coloured compounds. 3 They have high melting points. 4 They have variable oxidation numbers. A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

Part of a steel ship is protected from rusting using a sacrificial metal. What is a suitable sacrificial metal? A copper B zinc C silver D potassium

Which row gives a use for the named metal and two properties which both explain this use?

The apparatus used for the extraction of aluminium by electrolysis is shown. Which equation represents the reaction at the anode? A $\text{O}+2{\text{e}}^{-}\to {\text{O}}^{2-}$ B $2{\text{O}}^{2-}\to {\text{O}}_2+4{\text{e}}^{-}$ C ${\text{Al}}^{3-}\to \text{Al}+3{\text{e}}^{-}$ D ${\text{Al}}^{3+}+3{\text{e}}^{-}\to \text{Al}$

Which gas is both an element and present in clean, dry air? A argon B carbon dioxide C chlorine D water vapour

Oxides of nitrogen formed in a car's engine are removed using a catalytic converter. What happens to the oxides of nitrogen in the catalytic converter? A They are hydrated. B They are neutralised. C They are oxidised. D They are reduced.

What is the equation for photosynthesis? A $6{\text{CO}}_2+6{\text{H}}_2\text{O}\to {\text{C}}_6{\text{H}}_{12}{\text{O}}_6+6{\text{O}}_2$ B $2{\text{CO}}_2+2{\text{H}}_2\text{O}\to 2{\text{C}}_2{\text{H}}_5\text{OH}+3{\text{O}}_2$ C ${\text{C}}_6{\text{H}}_{12}{\text{O}}_6\to 2{\text{CO}}_2+2{\text{C}}_2{\text{H}}_5\text{OH}$ D ${\text{C}}_2{\text{H}}_5\text{OH}+3{\text{O}}_2\to 2{\text{CO}}_2+3{\text{H}}_2\text{O}$

Four statements about members of the same homologous series are listed. 1 They have the same volatility. 2 They have the same molecular formula. 3 They have the same functional group. 4 They have the same general formula. Which statements are correct? A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

Ethene reacts with steam to produce ethanol. Which row describes each compound?

Which process is used to make an alkene from a long-chain alkane? A combustion B condensation C cracking D polymerisation

Which fraction obtained from petroleum has the lowest boiling point? A diesel oil B fuel oil C kerosene D naphtha

Alkanes undergo substitution reactions with chlorine in the presence of ultraviolet light. Which equation shows a reaction of this type? A ${\text{C}}_3{\text{H}}_6+{\text{Cl}}_2\to {\text{C}}_3{\text{H}}_6{\text{Cl}}_2$ B ${\text{C}}_3{\text{H}}_8+{\text{Cl}}_2\to {\text{C}}_3{\text{H}}_6{\text{Cl}}_2+{\text{H}}_2$ C ${\text{C}}_3{\text{H}}_8+{\text{Cl}}_2\to {\text{C}}_3{\text{H}}_7\text{Cl}+\text{HCl}$ D ${\text{C}}_3{\text{H}}_6+{\text{Cl}}_2\to {\text{C}}_3{\text{H}}_5\text{Cl}+\text{HCl}$

Information about two reactions of ethene is listed. • Reaction 1 requires a nickel catalyst. • Reaction 2 requires an acid catalyst. Which substance reacts with ethene in each reaction?

Which process converts ${\text{CH}}_3{\text{CH}}_2\text{OH}$ to ${\text{CH}}_3\text{COOH}$? A bacterial oxidation B fermentation C catalytic addition of steam D catalytic addition of hydrogen

The structure of an ester is shown. Which row identifies the name of the ester and the two compounds from which it is made?

Which statements about monomers or polymers are correct? 1 Monomers are always joined together by addition reactions. 2 A polymer can be formed from a single type of monomer. 3 A polymer can be formed by joining two different types of monomer. 4 Water is always produced when monomer molecules join together. A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

The diagram shows the structure of a naturally occurring polymer, Q. What is Q? A an amino acid B nylon C a protein D PET

Which row shows how the boiling point and the melting point of water change when a soluble impurity is added to the water?

X is a white powder. The following tests are done on X. • When a few drops of aqueous sodium hydroxide are added to a solution of X, no precipitate is seen. • When X is heated with aqueous sodium hydroxide, no gas is formed. • X gives a lilac colour when put into a flame. • When acidified aqueous silver nitrate is added to a solution of X, a yellow precipitate is seen. What is X? A ammonium bromide B ammonium iodide C potassium bromide D potassium iodide