Feb/March 2025

Substance L does not keep a fixed shape and instead takes on the shape of the container holding it. What could the state of matter of substance L be?

Solids, liquids and gases

Antifreeze is made from a blend of water and ethylene glycol. Their displayed formulae are shown in the diagram. What is the molecular formula for ethylene glycol?

Formulae

The equation for the reaction between magnesium and oxygen is shown here. $\text{2Mg} + \text{O}_2 \rightarrow \text{2MgO}$ In an experiment, $6.0\,\text{g}$ of magnesium reacts with excess oxygen. Which mass of magnesium oxide, $\text{MgO}$, is formed?

The mole and the Avogadro constant

Which products are produced when dilute sulfuric acid is electrolysed?

Electrolysis

The diagram illustrates an experiment used to electroplate a nickel spoon with silver. Which row correctly states the positive electrode, the negative electrode and the electrolyte?

Electrolysis

As dilute sulfuric acid reacts with aqueous sodium hydroxide, the temperature of the solution increases. Which terms are used to describe this reaction?

Exothermic and endothermic reactions

Which statement is true of both physical and chemical changes?

Physical and chemical changes

A sample of calcium carbonate is made to react with dilute hydrochloric acid, giving a final gas volume of $60\,\text{cm}^3$. The reaction ends after $120\,\text{s}$. The experiment is then carried out again at a lower temperature, while every other condition remains unchanged. Which row gives the outcomes for the second experiment?

Rate of reaction

In which equation does iron undergo oxidation?

Redox

$\text{HOCl}$ acts as an acid. $\text{NH}_4\text{OH}$ acts as an alkali. Which row gives the ions present in the aqueous solutions that distinguish the acid from the alkali?

The characteristic properties of acids and bases

Which of these elements produce an oxide that, when it reacts with water, gives a blue solution with thymolphthalein? 1 calcium 2 carbon 3 sulfur

Oxides

The melting points and boiling points of the pure substances M, N and O are given below. Melting points / $^{\circ}\text{C}$: M $-114$, N $115$, O $-101$. Boiling points / $^{\circ}\text{C}$: M $78$, N $445$, O $-34$. The substances are chlorine, ethanol and sulfur. Which row matches M, N and O?

Solids, liquids and gases

A fertiliser sample is examined by heating it with aqueous sodium hydroxide. A colourless gas forms and turns damp red litmus paper blue. Which element, needed for plant growth, must be present?

Fertilisers

Solid magnesium carbonate, which is insoluble, is made to react with dilute sulfuric acid. magnesium carbonate + sulfuric acid $\rightarrow$ magnesium sulfate + water + carbon dioxide The procedure for producing crystals of magnesium sulfate is given below. step 1 Place excess magnesium carbonate into dilute sulfuric acid and stir the mixture. step 2 Filter off the mixture. step 3 Heat the filtrate until the crystallisation point is reached. step 4 Allow the filtrate to cool down. Which solid is left behind as the residue removed from the mixture in step 2?

Separation and purification

What trend is seen over the period from sodium to argon?

Arrangement of elements

Which statement concerning the element bromine is correct?

Group VII properties

X is a metallic element with a high density. In which part of the Periodic Table is X found?

Transition elements

Which of the following statements about the uses of metals is correct?

Uses of metals

Steel bridges are coated with paint to reduce the chance of rust developing on their surfaces. What makes steel rust?

Corrosion of metals

Which two metals are combined to produce brass?

Alloys and their properties

Metal M is located between zinc and iron in the reactivity series. Which of the following statements about metal M are true?

Reactivity series

What colour change occurs when water is added to anhydrous copper(II) sulfate?

Identification of ions and gases

Which statement accounts for the noble gases being unreactive?

Noble gases

Which statement concerning the composition of clean, dry air is correct?

Air quality and climate

Which row shows a source of methane and one harmful effect of methane?

Air quality and climate

Which of the following statements about alkenes is correct?

Alkenes

The table presents the formulae and names of some organic compounds. Which rows show the correct name for the formula displayed?

Naming organic compounds

Which gas makes up the largest proportion of natural gas?

Fuels

A sample of petroleum is split into three fractions, X, Y and Z, by fractional distillation. A few properties of X, Y and Z are shown. Which fraction has the longest carbon chain, and which fraction is the most volatile?

Fuels

Two salt solutions, P and Q, are examined. The table gives the results. What are P and Q?

Identification of ions and gases

A small amount of a solid, E, is placed into a large excess of aqueous ethanoic acid. No gas bubbles are observed and the solid dissolves, producing a colourless solution. What is solid E?

The characteristic properties of acids and bases

Ethanol is produced by two different methods. What starting materials are used in the two methods to produce ethanol?

Alcohols

Which reagent is used to test for chlorine?

Identification of ions and gases

What electronic configuration does a $\text{P}^{3-}$ ion have?

Atomic structure and the Periodic Table

Which statement regarding paper chromatography is correct?

Chromatography

The following data refer to four metal atoms or ions. Q: charge $+3$, electrons $10$, nucleon number $27$. R: charge $+2$, proton number $12$, nucleon number $24$. S: charge $+2$, electrons $10$, nucleon number $26$. T: proton number $16$, electrons $16$. Which two atoms or ions are isotopes of the same element?

Isotopes

Which row shows how the atoms change when a metal reacts with a non-metal?

Ions and ionic bonds

In the diagrams below, X and Y represent atoms of different elements. Which diagram correctly shows how the outer-shell electrons are arranged in a methane molecule?

Simple molecules and covalent bonds

Which option best describes the properties of graphite?

Giant covalent structures

Which row gives the formula of the substance named?

Formulae

The diagrams illustrate gas containers at the same temperature. Each container is the same size. Which container holds the gas at the greatest pressure?

Solids, liquids and gases

The equation for magnesium reacting with dilute sulfuric acid is given below. $\text{Mg} + \text{H}_2\text{SO}_4 \rightarrow \text{MgSO}_4 + \text{H}_2$ $[M_r: \text{MgSO}_4, 120]$ What mass of magnesium sulfate is produced when $12\,\text{g}$ of magnesium reacts completely with dilute sulfuric acid?

The mole and the Avogadro constant

An organic compound, Q, is made up of carbon, hydrogen and oxygen only. By mass, Q has $40.0\%$ carbon and $6.7\%$ hydrogen. What is the empirical formula of Q?

The mole and the Avogadro constant

The Avogadro constant has a value of $6.02 \times 10^{23}$. How many atoms are present altogether in $2.00\,\text{mol}$ of ammonia gas?

The mole and the Avogadro constant

Three aqueous solutions, L, M and N, are electrolysed with inert electrodes. L is concentrated hydrochloric acid. M is concentrated aqueous sodium chloride. N is dilute aqueous sodium chloride. Which of the solutions give a pale yellow-green gas at the anode?

Electrolysis

Dilute sulfuric acid is electrolysed with inert electrodes. What ionic half-equations show the reactions occurring at each electrode?

Electrolysis

Which of the following statements about hydrogen-oxygen fuel cells are correct?

Hydrogen–oxygen fuel cells

The reaction pathway diagram for the reaction between P and Q to produce R and S is shown. Which letter shows the enthalpy change for the reaction?

Exothermic and endothermic reactions

The equation for the complete combustion of methane is given below. $\text{CH}_4(g) + 2\text{O}_2(g) \rightarrow \text{CO}_2(g) + 2\text{H}_2\text{O}(g)$ Some bond energies are shown in the table. Calculate the enthalpy change for this reaction.

Exothermic and endothermic reactions

Which of these changes is a physical change?

Physical and chemical changes

Which statements account for why raising the temperature in a reaction involving gases increases the rate of reaction?

Rate of reaction

A cooling curve for a substance is displayed. Which statement is correct?

Solids, liquids and gases

The equation for the reaction between ammonia and oxygen is given below. $4\text{NH}_3(g) + 5\text{O}_2(g) \rightleftharpoons 4\text{NO}(g) + 6\text{H}_2\text{O}(g) \quad \Delta H = -909\,\text{kJ mol}^{-1}$ Which two alterations to the reaction conditions will both shift the equilibrium position to the right?

Reversible reactions and equilibrium

Mercury(II) oxide, $\text{HgO}$, breaks down on heating. The equation is shown. $2\text{HgO} \rightarrow 2\text{Hg} + \text{O}_2$ Why does this count as a reduction reaction?

Redox

Information about two dilute acids is shown below. Three statements about these acids are given. Which statements are correct?

The characteristic properties of acids and bases

Element E is a metal in Group I of the Periodic Table, whereas element G is a non-metal in Group VII. Both elements can form oxides. Which statement about these oxides is correct?

Oxides

Lead(II) sulfate is an insoluble salt. Which method would be suitable for obtaining pure lead(II) sulfate in solid form?

Separation and purification

Oxygen and sulfur are elements in the same group of the Periodic Table. Which statement about oxygen and sulfur is incorrect?

Arrangement of elements

Tennessine, Ts, is located at the bottom of Group VII in the Periodic Table. What predicted properties does tennessine have at room temperature?

Group VII properties

One example of sacrificial protection is the attachment of zinc blocks to the outside of a ship’s steel hull. Which statement explains why zinc is chosen to protect the iron in the steel against rusting?

Corrosion of metals

Which statement about alloys is right?

Alloys and their properties

When separate strips of aluminium foil and copper foil are heated in air, the copper foil reacts to form a black solid, whereas the aluminium foil does not react. Which statement accounts for these observations?

Corrosion of metals

Four samples of gases are let out into a room at the same time. The gases are carbon dioxide, $\text{CO}_2$, hydrogen chloride, $\text{HCl}$, hydrogen sulfide, $\text{H}_2\text{S}$, and nitrogen dioxide, $\text{NO}_2$. Which gas diffuses the most rapidly?

Diffusion

Which line shows the symbol equation for the formation of carbon monoxide and for the reduction of iron(III) oxide in a blast furnace?

Extraction of metals

A river water sample contains a high nitrate concentration from fertilisers. Which of the following statements about this river water are correct?

Fertilisers

Which of the following statements about the treatment of domestic water supplies are correct?

Water

A test to determine the percentage of oxygen in $150\,\text{cm}^3$ of polluted air is illustrated. The apparatus is then left for one week. After this period, the volume of gas in the measuring cylinder is $122\,\text{cm}^3$. What is the percentage of oxygen, to the nearest whole number, in the polluted air?

Air quality and climate

Nitrogen monoxide, NO, and carbon monoxide, CO, are each taken out of a car’s exhaust gases by a catalytic converter. Which statement explains how nitrogen monoxide and carbon monoxide are removed by a catalytic converter?

Redox

In a reaction analogous to the oxidation of ethanol, propan-1-ol is oxidised by acidified aqueous potassium manganate(VII). Which compound is formed when propan-1-ol is oxidised with acidified aqueous potassium manganate(VII)?

Alcohols

Methyl propane has the structural formula $\text{CH}_3\text{CH}(\text{CH}_3)\text{CH}_3$. The equation shows methyl propane reacting with chlorine. $\text{C}_4\text{H}_{10} + \text{Cl}_2 \rightarrow \text{C}_4\text{H}_9\text{Cl} + \text{HCl}$. From this reaction, how many structural isomers with molecular formula $\text{C}_4\text{H}_9\text{Cl}$ can be produced?

Alkanes

Which statements describe disadvantages of producing ethanol by fermentation?

Alcohols

Nylon is produced by a polymerisation reaction. Which row gives the type of polymerisation and names the other product formed in the reaction?

Polymers

Which ion produces a green precipitate with aqueous sodium hydroxide that then dissolves in excess aqueous sodium hydroxide?

Identification of ions and gases

Sulfur atoms are able to form the negative ion $\text{S}^{2-}$. The following three atoms or ions are given. • argon, $\text{Ar}$ • calcium, $\text{Ca}$ • oxide, $\text{O}^{2-}$ What number of these atoms or ions has the same electronic configuration as $\text{S}^{2-}$?

Atomic structure and the Periodic Table

Paper chromatography can be used to separate a mixture of soluble substances. The $R_f$ value can then be used to identify each substance. Which formula is used to calculate the $R_f$ value?

Chromatography

Element T contains two isotopes, $^{12}_{6}\text{T}$ and $^{14}_{6}\text{T}$. Which of the following statements about these isotopes is correct?

Isotopes

Lithium is placed in Group I of the Periodic Table. Nitrogen is placed in Group V of the Periodic Table. When lithium reacts with nitrogen, the ionic compound lithium nitride, $\text{Li}_3\text{N}$, is produced. What occurs to the electrons as lithium atoms and nitrogen atoms change into ions?

Ions and ionic bonds

Which covalent compound is shown accurately by the dot-and-cross diagram for the outer-shell electrons?

Simple molecules and covalent bonds

Which row correctly states the positive and negative particles found in a giant metallic lattice?

Metallic bonding

Which of the following is the correct formula for the named compound?

Formulae

The symbols and formulae are listed below. Ba2+ C Cl2 Cl- CO CO2 CuO H2 H2O K+ Na+ O2- Use only these symbols and formulae to answer the questions that follow. A symbol or formula may be chosen once, more than once, or not used at all.

Ions and ionic bonds

Table 2.1 presents data on how four different metals react with oxygen.

Reactivity series

A student explores how magnesium reacts with dilute sulfuric acid.

Rate of reaction

On Fig. 4.1, encircle the carboxylic acid functional group.

Formulae, functional groups and terminology

Using numbers only, state the percentage, by volume, of oxygen in clean, dry air.

The mole and the Avogadro constant

This question concerns ionic compounds.

Electrolysis

The halogens form a family of elements in the Periodic Table. Chlorine belongs to this family.

Group VII properties

Carbonyl chloride, COCl₂, is made by reacting carbon monoxide with chlorine. $\text{CO(g)} + \text{Cl}_2(\text{g}) \rightleftharpoons \text{COCl}_2(\text{g}) \quad \Delta H = -105\,\text{kJ/mol}$ This reaction is carried out in a closed system until equilibrium is established. The conditions used are 200 ^{\circ}C and 200 kPa.

Reversible reactions and equilibrium

Manganese is the element whose atomic number in the Periodic Table is 25. Calcium is the element whose atomic number in the Periodic Table is 20.

Transition elements

Two compounds, A and B, have the structural formulae shown below. A: CH₂=CHCH₃ B: CH₃CH=CHCH₃ A and B belong to one homologous series.

Alkenes