May/June 2025

What process occurs when water vapour turns into rain?

Solids, liquids and gases

The equation represents the thermal decomposition of magnesium carbonate. $\text{MgCO}_3 \rightarrow \text{MgO} + \text{CO}_2$ $[M_r: \text{MgCO}_3, 84]$ What mass of magnesium oxide is produced when $21.0\,\text{g}$ of magnesium carbonate is fully decomposed?

The mole and the Avogadro constant

A concentrated aqueous sodium chloride solution is electrolysed with inert electrodes. What is the main substance produced at the positive electrode (anode)?

Electrolysis

A hydrogen-oxygen fuel cell consumes $630\,\text{dm}^3$ of oxygen. This oxygen for the reaction is obtained from clean, dry air. What is the minimum volume of clean, dry air required to supply this amount of oxygen?

Hydrogen–oxygen fuel cells

Three statements concerning energy changes in chemical reactions are given. 1 For an endothermic reaction, the temperature of the surroundings rises. 2 For an exothermic reaction, thermal energy is absorbed from the surroundings. 3 On the reaction pathway diagram for an exothermic reaction, the products are at a lower energy level than the reactants. Which statements are correct?

Exothermic and endothermic reactions

When a small piece of a Group I metal is put into a large beaker of cold water, a reaction takes place. Four statements about this reaction are given. 1 The metal melts. 2 Hydrogen is produced. 3 Steam is produced. 4 The pH of the solution increases. Which statements about this reaction describe a physical change?

Physical and chemical changes

The equation representing the decomposition of hydrogen peroxide is given below. $2\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_2$ This reaction is exothermic. If a small amount of catalyst is added, oxygen is formed at a faster rate. Which statement correctly describes the catalyst?

Rate of reaction

The chemical equation for the reaction of copper(II) oxide with carbon is given below. $2\text{CuO} + \text{C} \rightarrow 2\text{Cu} + \text{CO}_2$ Which statement about this reaction is correct?

Redox

Which row shows the colours seen when thymolphthalein and methyl orange are each added separately to the solution named?

The characteristic properties of acids and bases

A blend of two substances, R and S, is warmed gently. The moist red litmus paper changes to blue. Which substances are R and S?

Identification of ions and gases

Which reactants are combined to produce the salt copper(II) sulfate?

Preparation of salts

The diagrams illustrate how particles are arranged in three different states of matter. Which row describes how the particles’ energy and particle motion change for the stated change of state?

Solids, liquids and gases

Which of the following statements about the Periodic Table is correct?

Atomic structure and the Periodic Table

A section of the Periodic Table is shown. Which element has the highest metallic character?

Arrangement of elements

E is an element in Group I of the Periodic Table. Two properties of E are given below. • Its melting point is higher than that of caesium. • Its density is lower than that of sodium. What is the identity of E?

Group I properties

The displacement reaction between aqueous halogen, $X_2$, and aqueous halide ions, $Y^-$, is represented by the equation below. $X_2\text{(aq)} + 2Y^-\text{(aq)} \rightarrow 2X^-\text{(aq)} + Y_2\text{(aq)}$ Which row correctly names $X_2$ and $Y^-$ and gives the reason that this reaction occurs?

Group VII properties

The following details about an element are given. melting point $/ ^\circ\text{C}$: $1555$ boiling point $/ ^\circ\text{C}$: $2963$ colour of oxide: brown use of element: as a catalyst Where is this element located in the Periodic Table?

Arrangement of elements

The table presents the observations made when the four metals, Q, R, S and T, are each placed separately in cold water and in dilute hydrochloric acid. Which row shows the metals in order of reactivity?

Reactivity series

Magnesium is reacted separately with dilute sulfuric acid and with steam. Which row correctly shows whether hydrogen is produced as a product in each reaction?

Reactivity series

Which of the following statements about aluminium are correct?

Properties of metals

Steel is an alloy of iron and one or more other elements. The table shows information about three common kinds of steel. Which rows pick out a type of steel that is suitable for making cutlery?

Alloys and their properties

The diagram illustrates an experiment used to investigate the corrosion of iron. What change occurs to the water level in tubes P and Q?

Corrosion of metals

An atom belonging to element Q has 19 electrons, 19 protons and 20 neutrons. What is Q?

Atomic structure and the Periodic Table

Fertilisers are used to supply the three elements required for better plant growth. Which two compounds could provide all three of these elements?

Fertilisers

Which substances can be used to show the presence of water?

Water

What substance is formed during the incomplete combustion of methane?

Fuels

Which row shows compounds that belong to the same homologous series?

Formulae, functional groups and terminology

Compound Z has the molecular formula $\text{C}_4\text{H}_{10}$. Which row shows the substance that reacts with Z and states the reaction type that takes place?

Alkanes

Which sequence gives the fractions separated from petroleum by fractional distillation, arranged in order of rising boiling point?

Fuels

Three statements about the cracking of larger alkane molecules are given. Which statements are correct?

Alkanes

A list of words used to describe organic compounds is shown. Which of these words describe ethene?

Alkenes

A student needs to measure out $25.00\ \text{cm}^3$ of dilute hydrochloric acid accurately. Which piece of apparatus is most appropriate?

Acid–base titrations

An excess of solid magnesium oxide is placed into dilute nitric acid. What separation technique is then used to remove the unreacted solid magnesium oxide once the reaction has ended?

Separation and purification

Which component of an atom has relative mass 1 and relative charge 0?

Atomic structure and the Periodic Table

Separate samples of four different aqueous metal nitrates are each examined using aqueous sodium hydroxide, dilute sulfuric acid and a flame test. Which row gives the correct collection of results for the named aqueous metal nitrate?

Identification of ions and gases

Which row shows the numbers of electrons, neutrons and protons in a particle that is an isotope of $^{11}_{5}\text{B}$?

Isotopes

Which of these statements about potassium iodide are correct?

Ions and ionic bonds

Which substances have one or more pairs of electrons shared between atoms?

Simple molecules and covalent bonds

At room temperature and pressure, which substance contains a giant covalent structure?

Giant covalent structures

Which row gives the correct formula for the substance named?

Formulae

Substance L has a melting point of $-7\,^{\circ}\text{C}$ and appears as a brown liquid at room temperature. What is the boiling point of pure L?

Solids, liquids and gases

The diagrams illustrate the structures of four molecules. Which statement about these molecules is correct?

Simple molecules and covalent bonds

The equation for magnesium reacting with oxygen is shown. $2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO}$ What mass of oxygen will react completely with $6\,\text{g}$ of magnesium?

The mole and the Avogadro constant

The diagram illustrates a basic electrolytic cell used in an electrolysis experiment. Three components of the electrolytic cell are labelled X, Y and Z. Which row gives the correct labels to substitute for X, Y and Z in the diagram?

Electrolysis

Which equation gives the overall reaction that produces electricity in a hydrogen-oxygen fuel cell?

Hydrogen–oxygen fuel cells

Which reaction pathway diagram shows the greatest rise in the temperature of the surroundings? (The scale on the y-axis is identical in each diagram.)

Exothermic and endothermic reactions

Which process is one that involves a chemical change?

Physical and chemical changes

The total amount of gas formed in two separate experiments is recorded against time. A graph showing the results from the two experiments is given. Which point indicates the highest rate of reaction?

Rate of reaction

The equation for the reaction between sulfur dioxide and oxygen is shown. $2\text{SO}_2 + \text{O}_2 \rightleftharpoons 2\text{SO}_3$ What does the symbol $\rightleftharpoons$ mean?

Reversible reactions and equilibrium

Which of the following reactions are redox reactions?

Redox

Which row gives the aqueous solution for the pH shown?

The characteristic properties of acids and bases

Which row shows how a gas’s volume changes when its temperature is raised at constant pressure and when its pressure is raised at constant temperature?

Solids, liquids and gases

Which regions of the Periodic Table include elements that form only basic oxides?

Oxides

Of the statements about elements in the Periodic Table, which one is correct?

Atomic structure and the Periodic Table

Which row shows the pattern in the properties of the elements lithium to sodium to potassium?

Group I properties

Which statements concerning the halogens are correct?

Group VII properties

Zirconium is classified as a transition element. State one property of zirconium?

Transition elements

Some gases are monoatomic, chemically unreactive and have eight electrons in their outer shell. Which gases match this description?

Noble gases

Which of the following statements about metals are correct?

Properties of metals

Four metals, P, Q, R and S, are each reacted separately with dilute hydrochloric acid. The table gives the observation for each metal. What is the reactivity order of these four metals, from the most reactive to the least reactive?

Reactivity series

The diagram shows iron nails that are left for one week in separate test-tubes under the conditions illustrated. Which test-tubes provide evidence that rusting has occurred after one week?

Corrosion of metals

Pure metals may be mixed to form alloys. Why are alloys sometimes chosen instead of the metals from which they are produced?

Alloys and their properties

Nitrogen dioxide is a red-brown gas that is denser than air. The diagram illustrates the setup of two gas jars containing nitrogen dioxide and air, with a glass plate between them. The glass plate is taken away, and the gas jars are left for $24$ hours. Which diagram shows the gas jars after $24$ hours?

Diffusion

In the experiment illustrated, $100\,\text{cm}^3$ of clean, dry air is sent to and fro through a tube packed with heated copper until the air volume no longer falls. The entire gas sample is then forced into a single syringe. What reading is obtained on this gas syringe?

Air quality and climate

Sulfur dioxide, carbon monoxide and oxides of nitrogen are gaseous pollutants present in the air. Which of these pollutants cause acid rain?

Air quality and climate

The formulae of three organic compounds are given below. Which of these compounds are in the same homologous series?

Formulae, functional groups and terminology

Which fuel might be gasoline?

Fuels

Three hydrocarbons are each mixed separately with aqueous bromine. Which row shows the correct observation for every hydrocarbon?

Alkenes

Which compound is produced when ethene reacts with steam?

Alcohols

Which of the following statements about ethanoic acid are correct?

Carboxylic acids

Which statement accounts for why plastic bags made from poly(ethene) build up in oceans?

Polymers

Which diagram illustrates the correct solvent level at the beginning of a chromatography experiment?

Chromatography

Which method is used to separate a mixture of liquids that have different boiling points?

Separation and purification

Which substance consists of one element together with one compound?

Elements, compounds and mixtures

Four separate colourless solutions are each examined individually with aqueous sodium hydroxide and with acidified aqueous silver nitrate. Which row gives the results for sodium chloride?

Identification of ions and gases

Which statement gives the definition of the atomic number of an element?

Atomic structure and the Periodic Table

What distinguishes isotopes of the same element?

Isotopes

When sodium chloride is produced from its elements, each chlorine atom ........1........ one ........2........ . Which words correctly fill gaps $1$ and $2$?

Ions and ionic bonds

In the molecules $\text{CH}_4$, $\text{HCl}$ and $\text{H}_2\text{O}$, which atoms make use of all the electrons in their outer shells for bonding?

Simple molecules and covalent bonds

Which substance is characterised by a giant covalent structure?

Giant covalent structures

Liquid iron is cooled until it turns into solid iron. Which statement about the particles in iron is correct?

Solids, liquids and gases

Define relative atomic mass.

Relative masses of atoms and molecules

Which row correctly describes the electrolysis of molten potassium bromide?

Electrolysis

What products are formed in a hydrogen-oxygen fuel cell?

Hydrogen–oxygen fuel cells

When ammonium nitrate is mixed with water, the temperature of the mixture falls. The ammonium nitrate can be obtained again by removing the water through evaporation. Which statement accounts for these observations?

Exothermic and endothermic reactions

Magnesium is allowed to react with dilute hydrochloric acid. The table gives the total volume of hydrogen produced at intervals of 15 seconds. In which time interval is the reaction rate greatest?

Rate of reaction

Which substance produces a blue solution when it is mixed with water?

Transition elements

Steam combines with carbon to form carbon monoxide and hydrogen. $\text{C(s)} + \text{H}_2\text{O(g)} \rightarrow \text{CO(g)} + \text{H}_2\text{(g)}$ Which substance is reduced in this reaction?

Redox

The three compounds are aluminium nitrate, ammonium chloride and ammonium nitrate. Each compound is heated with aqueous sodium hydroxide. Which of the compounds will produce ammonia?

Identification of ions and gases

A solution that contains hydroxide ions, $\text{OH}^-\text{(aq)}$, is introduced into a solution containing hydrogen ions, $\text{H}^+\text{(aq)}$. An equation for the reaction is shown. $\text{H}^+\text{(aq)} + \text{OH}^-\text{(aq)} \rightarrow \text{H}_2\text{O(l)}$ Which statement about this reaction is correct?

The characteristic properties of acids and bases

Which compound should be classified as an acidic oxide?

Oxides

Which diagram represents a mixture made up of an element and a compound?

Elements, compounds and mixtures

Which statement gives the description of a hydrated salt?

Formulae

In the Periodic Table, how does metallic character change as you move from left to right across a period?

Arrangement of elements

Lithium, sodium and potassium are elements in Group I of the Periodic Table. Which of the following statements about these elements are correct?

Group I properties

X, Y and Z are each one of the three elements chlorine, bromine and iodine. If aqueous X is mixed with aqueous ions of Y, no reaction occurs. If aqueous Y is mixed with aqueous ions of Z, no reaction occurs. Which statement is correct?

Group VII properties

Which row gives the characteristics of a transition element?

Transition elements

Which of the following statements about the elements in Group VIII are correct?

Noble gases

Sulfur and potassium are two elements in the Periodic Table. Which row shows the element with the greater thermal conductivity and the element with the lower malleability?

Properties of metals

Three statements about aluminium and copper are given. Which statements account for aluminium being chosen rather than copper for overhead power cables?

Uses of metals

The table provides some details on how four metals, J, K, L and M, react. J reacts with steam and hydrochloric acid, but not with cold water. K reacts with hydrochloric acid, but not with steam or cold water. L reacts with hydrochloric acid and with cold water. M does not react with hydrochloric acid. What is the reactivity order of metals J, K, L and M?

Reactivity series

What is rust’s chemical name?

Corrosion of metals

Which statement correctly describes elements and their atoms?

Elements, compounds and mixtures

Water taken from natural sources may have many substances dissolved in it. Which of these substances are often harmful to aquatic life?

Water

Which gas makes up over 30% of clean, dry air?

Air quality and climate

Farmers add fertilisers to replenish the soil with the elements removed by the crops they grow. Which elements in the soil are replenished when fertilisers are added?

Fertilisers

The reaction equation for carbon dioxide and water, with chlorophyll and sunlight present, is displayed below. $\text{carbon dioxide} + \text{water} \xrightarrow[\text{sunlight}]{\text{chlorophyll}} \text{glucose} + \text{oxygen}$ Which process is represented by this equation?

Air quality and climate

Which of the following statements about members of a homologous series is correct?

Formulae, functional groups and terminology

Four organic compounds, W, X, Y and Z, have the molecular formulae below. W: $\text{C}_3\text{H}_8\text{O}$, X: $\text{C}_3\text{H}_6$, Y: $\text{C}_4\text{H}_8\text{O}_2$, Z: $\text{C}_6\text{H}_{14}$ Which of the statements concerning compounds W, X, Y and Z is correct?

Formulae, functional groups and terminology

Fractional distillation is used to divide petroleum into several useful fractions. Which statement about the properties of petroleum fractions is correct?

Separation and purification

Which of these statements concerning the alkanes are correct?

Alkanes

Which products may result from cracking one molecule of hexane, $\text{C}_6\text{H}_{14}$?

Alkanes

Three coloured inks, P, Q and R, are examined by paper chromatography. The chromatogram is displayed. Which statement is correct?

Chromatography

An atom of the element erbium is shown as $^{167}_{68}\text{Er}$. Which row gives the numbers of protons, neutrons and electrons in this atom?

Atomic structure and the Periodic Table

The table gives the outcomes of two different tests carried out on a sample of aqueous T. Flame test: gave a yellow flame. Add dilute nitric acid: effervescence. What is T?

Identification of ions and gases

Rubidium belongs to Group I of the Periodic Table, whereas bromine belongs to Group VII of the Periodic Table. Rubidium and bromine react together to make an ionic compound. Which row indicates the electron transfer for rubidium and gives the correct formula for the rubidium ion produced?

Ions and ionic bonds

Which dot-and-cross diagram shows the electronic arrangement of the outer-shell electrons in ammonia, $\text{NH}_3$?

Simple molecules and covalent bonds

Which statements about graphite are true?

Giant covalent structures

Which equation shows the reaction between magnesium and dilute hydrochloric acid?

The characteristic properties of acids and bases

The relative formula mass, $M_r$, of calcium carbonate, $\text{CaCO}_3$, is 100. What mass of carbon is contained in $100\,\text{g}$ of calcium carbonate?

Relative masses of atoms and molecules