0620 Chemistry June 2025 Question Paper 21

A gas is placed in a sealed container with a fixed volume. The gas is heated. Which statements are correct? The gas molecules move around faster.

The gas particles collide with the walls of the container more frequently.

The pressure in the container decreases.

4 The only naturally occurring isotopes in a sample of europium are 151Eu and 153Eu. This sample of europium has a relative atomic mass, Ar, of 152.

What is the percentage of 151Eu present in this sample to three significant figures? A 0.987% B 50.0% C 76.0% D 98.7%

5 Which statement about potassium chloride is correct? A It has a high melting point because it is a giant structure with strong covalent bonds. B It conducts electricity when solid because of its oppositely charged ions. C It conducts electricity when molten because its ions can move. D It is insoluble in water because of its strong bonding.

Which statement about the heating curve is correct?

Which statement about silicon(IV) oxide is correct?

Three organic molecules are described. ● The molecular formula of propanoic acid is CH3CH2COOH. ● The molecular formula of lactic acid is CH3CH(OH)COOH. ● A glucose molecule consists of 6 carbon atoms, 6 oxygen atoms and 12 hydrogen atoms only. Which molecules have the same empirical formula?

Calcium carbonate reacts with dilute hydrochloric acid. The equation for the reaction is shown. CaCO3 + 2HCl  CaCl 2 + H2O + CO2 1.00 g of calcium carbonate is added to 50.0 cm3 of 0.0500 mol / dm3 hydrochloric acid. Which volume of carbon dioxide is made in this reaction?

The diagram shows the electroplating of a steel object. steel object copper electrode aqueous copper(II) sulfate + – power supply A student makes three statements. The steel object turns a reddish-brown colour. The aqueous copper(II) sulfate changes to a paler blue colour. The copper electrode becomes thinner. Which statements are correct?

Concentrated aqueous sodium chloride is electrolysed using inert electrodes. Which equation shows the correct ionic half-equation for the reaction at the anode?

Which equation represents the overall reaction in a hydrogen–oxygen fuel cell?

Water is added to anhydrous copper(II) sulfate in a test-tube. The mixture becomes hot. Which type of reaction and reaction pathway diagram apply to this reaction? type of reaction reaction pathway diagram

The equation represents the reaction between ethanoic acid and ethanol. CH3COOH + CH3CH2OH CH3COOCH2CH3 + H2O Which type of reaction does this show?

The graph shows the results of adding excess calcium carbonate to hydrochloric acid at 50 °C and at 30 °C. Only the temperature is changed. total volume of carbon dioxide given off / cm3 time / s 50 °C 30 °C Which row describes the reacting particles at 30 °C compared to those at 50 °C? frequency of collisions between particles average kinetic energy of particles

Industrially, ammonia is made by the Haber process. The equation is shown. N2(g) + 3H2(g) 2NH3(g) H = –92 kJ / mol The conditions used are 450 °C and 200 atm. Which statements about the conditions are correct? Temperatures below 450 °C give a lower rate of reaction. Temperatures below 450 °C give a lower yield of ammonia. Pressures above 200 atm give a lower yield of ammonia. Pressures above 200 atm are too expensive to maintain.

Ethanol is warmed with acidified aqueous potassium manganate(VII). Which row describes the type of reaction of the ethanol and the colour change observed in the reaction mixture? type of reaction colour change

Two experiments involving acids R or S are done. ● 0.10 mol of acid R completely dissolves in 500 cm3 of water. 0.0048 mol of acid R is dissociated in the solution. ● 0.10 mol of acid S completely dissolves in 500 cm3 of water. 0.0179 mol of acid S is dissociated in the solution. Which statement about acids R and S is correct?

Lead(II) sulfate is an insoluble salt. Which process is not used to prepare a pure sample of this salt?

The formulae of two hydrated salts are shown. ● CuSO4•xH2O ● CoCl 2•yH2O What are the values of x and y? x y

The properties of the elements change from left to right across the Periodic Table. Which statement describes how the properties change across Period 3?

Which property decreases down Group VII of the Periodic Table, from chlorine to iodine?

Some properties of elements are listed. They have good electrical conductivity. They have high melting points. They are malleable. They have ions with variable oxidation numbers. Which properties are correct for both iron and lithium?

Two statements about noble gases are listed. Noble gases are reactive, monatomic gases. Noble gases all have a full outer shell of electrons. Which statements about noble gases are correct?

Which statement about the properties and uses of copper is correct?

Three statements about solid Z are listed. ● It reacts with dilute hydrochloric acid to produce hydrogen. ● It reacts very slowly with cold water and quickly with steam. ● It is a good thermal conductor. What is solid Z?

Four metals J, K, L and M are added separately to aqueous solutions of their ions. The results are shown. aqueous ions metal J2+ K2+ L2+ M2+ J     key K      = reaction L      = no reaction M     Which statement about the metals is correct?

Which process is used in the extraction of iron from hematite?

Galvanising prevents iron from rusting. Which statements about galvanising are correct? Galvanising involves coating the iron with silver. Galvanising prevents oxygen and water from coming into contact with the iron. Galvanising works because the metal coating loses electrons more readily than iron.

Nitrogen, phosphorus and potassium are essential elements for improved plant growth. Which mixture provides all three essential elements? mixture formulae

Which statements help explain why an increasing amount of carbon dioxide or methane in the atmosphere causes global warming? Carbon dioxide absorbs thermal energy from the Earth. Methane does not absorb thermal energy from the Sun. Carbon dioxide does not reflect thermal energy from the Sun to the Earth. Methane reflects thermal energy from the Earth back to the Earth.

The exhaust gases from cars contain oxides of nitrogen. How are these oxides of nitrogen formed?

The structural formula of methyl ethanoate is CH3COOCH3. Which compounds are structural isomers of methyl ethanoate? HCOOCH2CH3 CH3CH2COOH HOCH2CH2CH2OH

What is the total number of covalent bonds in one molecule of propane?

Industrially, ethanol is produced by fermentation or by the reaction of ethene with steam. Which row is correct? fermentation ethene + steam

Some properties of an organic compound, J, are listed. ● It is a liquid at room temperature. ● It is soluble in water. ● A solution of J reacts with calcium carbonate to form carbon dioxide. ● A solution of J has a pH of 3. In which homologous series does J belong?

The structures of two monomers that are used to make a condensation polymer are shown. HO

Which item of apparatus is used to measure 25.0 cm3 of aqueous sodium hydroxide?

Which method is used to obtain copper(II) sulfate crystals from an aqueous solution of copper(II) sulfate?

A mixture of four different colourless amino acids is analysed by paper chromatography. The final chromatogram is shown. solvent front baseline Why does the chromatogram only show three spots?