0620 Chemistry June 2025 Question Paper 23

Which two changes, when applied at the same time to a fixed amount of gas, cause the greatest increase in volume of the gas? change in pressure change in temperature

Solid G is heated until it melts. It is then left to cool to room temperature. The graph shows the cooling curve for G. X Y time temperature Four statements about the cooling curve between X and Y are listed. The speed of the molecules of G decreases. The molecules of G become less closely packed.

Thermal energy is released by the molecules of G to the surroundings.

G changes from solid to liquid. Which statements are correct?

The diagram shows the positions of elements P and Q in the Periodic Table. P Q What is the formula of the compound that is formed between P and Q?

Which statement about ionic compounds is correct?

The equation for the reaction between iron(III) chloride and sodium hydroxide is shown. FeCl 3(aq) + 3NaOH(aq)  Fe(OH)3(s) + 3NaCl (aq) What is the ionic equation for this reaction?

A compound is analysed and found to contain 85.7% carbon and 14.3% hydrogen only. What is its empirical formula?

Aqueous barium hydroxide, Ba(OH)2, reacts with dilute nitric acid, HNO3. The products are aqueous barium nitrate, Ba(NO3)2, and water. In a titration, 15.2 cm3 of 0.75 mol / dm3 aqueous barium hydroxide is required to neutralise 20.0 cm3 of dilute nitric acid. What is the concentration of the nitric acid?

Which particles are responsible for the transfer of charge in the external circuit during the electrolysis of molten lead(II) bromide?

Two statements about hydrogen are listed. Hydrogen is used as a fuel. When hydrogen burns in the air to form water, thermal energy is produced. Which conclusion about these statements is correct?

Concentrated aqueous copper(II) chloride is electrolysed using carbon electrodes. What is formed at each electrode? negative electrode positive electrode

Which row describes an exothermic reaction? sign of enthalpy change, H temperature of the surroundings

A reaction pathway diagram is shown. reactants products energy progress of reaction X Y Which row shows the correct labels for X and Y and the type of reaction taking place? X Y type of reaction

The rate of reaction between magnesium and dilute hydrochloric acid is increased by increasing the concentration of the acid. How does this affect the reacting particles? collision rate of particles proportion of particles with sufficient energy to react

The reaction between aqueous iron(III) ions, Fe3+, and aqueous thiocyanate ions, SCN–, is reversible. The equation for the reaction is shown. Fe3+(aq) + SCN–(aq) FeSCN2+(aq) yellow colourless red At equilibrium, the concentrations of Fe3+ ions, SCN– ions, and FeSCN2+ ions are identical, and the mixture appears orange. When a few drops of aqueous thiocyanate ions are added to the mixture, a new equilibrium forms. How does the colour of the mixture change?

The equation for the reaction between iron(II) sulfate and bromine is shown. 6FeSO4 + 3Br2  2Fe2(SO4)3 + 2FeBr3 Which row identifies the oxidising agent and the reducing agent? oxidising agent reducing agent

The equation represents a redox reaction. 2Al + Fe2O3  2Fe + Al 2O3 What is the change in the oxidation number of iron in this reaction?

Aqueous ammonia forms an equilibrium with water. NH3 + H2O NH4 + + OH– In this equilibrium, which particle acts as an acid and which particle acts as a base? acid base

Which row identifies an acidic oxide, a basic oxide and an amphoteric oxide? acidic basic amphoteric

A Group I metal (lithium or potassium) is reacted with a Group VII element (chlorine or iodine). Which compound is formed when the Group I metal of highest density reacts with the Group VII element of lowest density?

Element X is in the same group of the Periodic Table as silicon. An atom of element X has more protons than a silicon atom. Which element could be X?

Which statement about the elements in Group VIII is correct?

Which element is a transition element? melting point in °C density at r.t.p. in g / cm3 colour of oxide at r.t.p.

Four test-tubes contain dilute hydrochloric acid. Each test-tube has one piece of a different metal added to it. The metals are copper, iron, magnesium and zinc. Which test-tube contains iron and dilute hydrochloric acid?

Brass is a mixture of copper and zinc. Which statement describes and explains the relative strength of brass compared to copper?

A sample of calcium carbonate is heated strongly, and substances U and V are formed. Substance U is a white solid. Substance V is a colourless gas. What are substances U and V? U V

A sample of water taken from a river contains harmful microbes. What is a source of harmful microbes in the river water?

Anhydrous copper(II) sulfate and anhydrous cobalt(II) chloride change colour when water is added to them. Which row shows the correct colour changes? copper(II) sulfate cobalt(II) chloride

Which gas contributes to increased global warming?

Which statement describes how greenhouse gases increase global warming?

Nitrogen monoxide is produced in a car engine when petrol is burned. The gases from the car engine are passed through a catalytic converter. In the catalytic converter, the nitrogen monoxide, NO, reacts with carbon monoxide, CO, to form nitrogen and carbon dioxide. Which statement is not correct?

The displayed formula of but-2-ene is shown.

Which row describes two characteristics of members of the same homologous series? characteristic 1 characteristic 2

Compound W is a hydrocarbon that contains single bonds only. Which homologous series contains W?

Methane forms chloromethane in a photochemical reaction using ultraviolet light. Which statement about this reaction is correct?

Which statement about polymers is correct?

The steps used to separate a mixture of a soluble solid and an insoluble solid are listed. ● A solution is made by adding the mixture to a suitable ......1...... . ● The mixture is stirred and then poured through a filter funnel lined with filter paper. ● The insoluble solid is collected on the filter paper as the ......2...... . Which words complete gaps 1 and 2?

Which items of apparatus are used to separate a mixture of liquids with different boiling points?

In paper chromatography, what is the equation for the Rf value?