Oct/Nov 2025

Which process refers to a substance moving very slowly from a region of high concentration to a region of low concentration?

Diffusion

Which row shows the product formed at each electrode when molten zinc chloride is electrolysed with inert electrodes?

Electrolysis

Which equation shows the reaction occurring in a hydrogen-oxygen fuel cell?

Hydrogen–oxygen fuel cells

What is always formed when a fuel is burned?

Fuels

The reaction pathway diagram displays the energy of the reactants and products during a chemical reaction. Which row identifies the enthalpy change and the kind of reaction shown?

Exothermic and endothermic reactions

Magnesium is allowed to react with dilute hydrochloric acid at the same concentration in four experiments under different conditions. Which reaction was completed in the least time?

Rate of reaction

When blue hydrated copper(II) sulfate is heated, it forms a white solid. If water is then added, the solid becomes blue again. Which term describes the reaction of hydrated copper(II) sulfate?

Physical and chemical changes

Iron(III) chloride, $\text{FeCl}_3$, is a brown solid. What does (III) in the name indicate?

Formulae

What units are used for concentration?

The mole and the Avogadro constant

Which two reactants are each soluble in water and combine to produce a precipitate?

Elements, compounds and mixtures

The four oxides below are given. 1 lithium oxide. 2 phosphorus oxide. 3 sodium oxide. 4 sulfur dioxide. Which of these oxides are basic?

Oxides

The atomic number and nucleon number for a potassium atom are given. How many protons, neutrons and electrons are present in the potassium ion, $\mathrm{K}^{+}$, formed from this potassium atom?

Atomic structure and the Periodic Table

Cobalt is a typical transition element. Which statement concerning cobalt is correct?

Transition elements

Which diagrams illustrate the electronic configuration of an atom of a noble gas?

Noble gases

Which statement gives a description of the alloy brass?

Alloys and their properties

The outcomes for how metals W, X, Y and Z react with cold water and dilute acid are given. What is the reactivity order of the metals?

Reactivity series

Several ways of stopping iron from rusting are given. 1 alloying with chromium. 2 greasing. 3 painting. Which of these are barrier methods?

Corrosion of metals

Which metal is obtained from bauxite by electrolysis?

Extraction of metals

Which of the following statements about water is true?

Water

How is ethanol structured?

Alcohols

Which statement is correct about alkanes?

Alkanes

Which row identifies a harmful effect of the pollutant named?

Air quality and climate

Magnesium belongs to Group II and Period 3 of the Periodic Table. Which row gives the charge on a magnesium ion and the electronic configuration of a magnesium ion?

Ions and ionic bonds

Which class of compounds shares the same general formula?

Formulae, functional groups and terminology

Several fractions derived from petroleum are shown. Which rows are correct?

Fuels

Four different substances, or classes of substance, are shown. 1 hydrogen 2 alcohols 3 alkenes 4 carboxylic acids Which substances are made when larger alkane molecules are cracked?

Alkenes

Which row gives the conditions needed to produce ethanol from ethene and steam?

Alcohols

Which of these statements about aqueous ethanoic acid is correct?

The characteristic properties of acids and bases

This equation shows a polymerisation reaction. $n\,\text{CH}_2{=}\text{CH}_2 \rightarrow [\text{-CH}_2-\text{CH}_2-]_n$ Which statements below are correct?

Polymers

A wax sample is heated. It starts to melt at $45\,^\circ\text{C}$ and has completely melted by $49\,^\circ\text{C}$. A liquid sample is heated. It starts to boil at $141\,^\circ\text{C}$ and stays at $141\,^\circ\text{C}$ during boiling. Which conclusion can be drawn from these results?

Solids, liquids and gases

Chromatography is used to analyse four dyes, P, Q, R and S. The solvent is water. The chromatogram obtained is shown below. Which statement concerning the dyes is correct?

Chromatography

The equipment used for separating a mixture is shown. What mixture is it?

Separation and purification

Two different white solids are heated, and the gases produced are tested. The gas from solid 1 turns moist red litmus paper blue. The gas from solid 2 relights a glowing splint. Which row shows the gases produced from each solid?

Identification of ions and gases

Sodium belongs to Group I of the Periodic Table, while chlorine belongs to Group VII of the Periodic Table. These two elements react together to make a compound. Which statement about how sodium atoms and chlorine atoms combine is correct?

Ions and ionic bonds

Which ion in aqueous solution produces a blue precipitate when aqueous sodium hydroxide is added?

Identification of ions and gases

Strontium nitrate is an ionic compound. Cyclohexane is a covalent compound. Which row gives a property of each compound?

Ions and ionic bonds

Which element makes covalent bonds with hydrogen?

Simple molecules and covalent bonds

Which of the following statements about graphite and diamond is correct?

Giant covalent structures

Carbon dioxide gas reacts with aqueous calcium hydroxide to produce calcium carbonate. Which equation shows this reaction?

Preparation of salts

The combustion equation for magnesium is given below. $2\mathrm{Mg} + \mathrm{O}_2 \rightarrow 2\mathrm{MgO}$. What mass of magnesium oxide is produced when $9.6\,\mathrm{g}$ of magnesium reacts completely?

The mole and the Avogadro constant

Water can be found as ice, liquid water and steam. In which of these states can water be compressed easily until its volume is reduced to half?

Solids, liquids and gases

Which equation shows the complete combustion of butane, $\mathrm{C}_4\mathrm{H}_{10}$?

Fuels

For calcium sulfate, $\mathrm{CaSO}_4$, what is the relative formula mass?

Relative masses of atoms and molecules

What substance is formed at each electrode when molten silver iodide is electrolysed with inert electrodes?

Electrolysis

Which row identifies the product at each electrode when dilute sulfuric acid is electrolysed with inert electrodes?

Electrolysis

Which experiment releases the most energy as heat?

Exothermic and endothermic reactions

Which test-tube shows a physical change?

Physical and chemical changes

Which pieces of apparatus are needed to measure how temperature affects the rate of any reaction? 1 balance 2 gas syringe 3 stop-watch 4 thermometer

Rate of reaction

If pink cobalt(II) chloride is heated, it changes into a blue solid and water is produced. If water is then added to the blue solid, heat is given out and a pink solid is formed. Which row states the reaction type and the pink cobalt(II) chloride?

Physical and chemical changes

What oxidation number does iron have in iron(III) oxide, $\mathrm{Fe}_2\mathrm{O}_3$?

Redox

Which of these substances will react with dilute hydrochloric acid to produce aqueous copper(II) chloride? 1 copper 2 copper(II) oxide 3 copper(II) carbonate 4 copper(II) hydroxide

Preparation of salts

Sulfur has a melting point of $113\,^{\circ}\mathrm{C}$. Which row shows how sulfur particles are arranged and how they move at $25\,^{\circ}\mathrm{C}$?

Solids, liquids and gases

A few drops of thymolphthalein and methyl orange are each added separately to two test-tubes that contain solution X. Next, solution Y is added to both test-tubes until it is in excess. The indicator colours before and after the addition of solution Y are shown. What is solution Y?

The characteristic properties of acids and bases

Which combination of solids is separated by adding water, stirring, and then carrying out filtration?

Separation and purification

The nature of the elements and the charges carried by their ions vary across the Periodic Table. Which row gives the elements on the left-hand side and the elements on the right-hand side of the Periodic Table?

Atomic structure and the Periodic Table

Which statement describes the overall trend down Group I?

Group I properties

Which statement describes how the named halogen looks at room temperature and pressure?

Group VII properties

Osmium is a transition element. Which row shows the properties expected for osmium?

Transition elements

Which of the following statements about the element neon, Ne, is correct?

Atomic structure and the Periodic Table

Substance G reacts with: • dilute acids to give hydrogen • steam to form a basic oxide • oxygen to form a basic oxide. What is substance G?

Reactivity series

Which row gives two properties and one use of the named metal?

Properties of metals

The following four methods can be used to stop iron rusting. 1 alloying 2 coating with plastic 3 greasing 4 painting. Which of these are barrier methods?

Corrosion of metals

Solid Y is placed into a surplus of hot water. A blue solution is produced, while a brown solid is left behind. The brown solid is then filtered off and dried. This brown solid conducts electricity. What is Y?

Properties of metals

Hematite is used to extract iron in a blast furnace. Which reaction involves thermal decomposition?

Extraction of metals

Clean, dry air is made up of nitrogen, oxygen and small quantities of other gases. The noble gases are missing from the table. Which row gives the composition of clean, dry air?

Noble gases

Some materials present in water from natural sources may be harmful. Which substance contains microbes that cause disease?

Water

Gas X is a waste gas released during digestion in animals. Gas Y is formed when gas X is combusted with too little oxygen. Gas Z is formed when gas X is combusted with too much oxygen. What are X, Y and Z?

Fuels

Which of the following statements about photosynthesis is correct?

Physical and chemical changes

L and M belong to two different homologous series. The first three compounds in homologous series L all decolourise aqueous bromine. The first three compounds in homologous series M all dissolve in water and form solutions with a pH below 7. What are the general formulae of homologous series L and M?

Formulae, functional groups and terminology

Which structure shows an unsaturated hydrocarbon?

Alkenes

Petroleum is a mixture of compounds. Which elements occur in all of these compounds? 1 carbon 2 hydrogen 3 oxygen

Elements, compounds and mixtures

Which statement about ethanol explains why it is used as a fuel?

Fuels

The table lists the outcomes of two tests carried out on an aqueous solution made from a solid. Test: add acidified silver nitrate → a white precipitate forms. Test: add aqueous sodium hydroxide → a green precipitate forms and then dissolves in excess sodium hydroxide. Identify the solid.

Identification of ions and gases

Which of the following statements about atomic structure is correct?

Atomic structure and the Periodic Table

W is a blend of coloured dyes. It is believed to contain dyes P, Q, R or S. A sample of W is separated using chromatography. The chromatogram is shown. What information does the chromatogram provide?

Chromatography

The diagram presents the electronic configuration of a particle that has a nucleon number of 40. The table lists the ideas proposed by three students, 1, 2 and 3, for identifying the particle. Student 1: Ar; Student 2: Cl; Student 3: $\mathrm{Ca}^{2+}$. Which of the students are correct?

Atomic structure and the Periodic Table

How are different atoms of the same element, with the same number of protons but different numbers of neutrons, defined?

Isotopes

The electron arrangements of atoms Q and R are shown. Q and R form an ionic compound. What is the formula of this compound?

Ions and ionic bonds

Which of the following properties are characteristic of simple molecules? 1 a melting point that is high; 2 high electrical conductivity; 3 a boiling point that is low; 4 a large degree of malleability.

Simple molecules and covalent bonds

Diamond is exceptionally hard and does not allow electricity to pass through it. Which statement explains these properties?

Giant covalent structures

Substances can be found as solids, liquids or gases. In which states of matter are the particles roughly the same distance apart?

Solids, liquids and gases

Which statement gives the definition of the term molecular formula?

Formulae

What is the relative formula mass, $M_r$, for calcium hydroxide, $\mathrm{Ca(OH)_2}$?

Relative masses of atoms and molecules

Which statements describe why metal objects are electroplated?

Electrolysis

Three statements concerning a hydrogen-oxygen fuel cell are provided. Which of the statements are correct?

Hydrogen–oxygen fuel cells

Which reaction pathway diagram shows an endothermic reaction?

Exothermic and endothermic reactions

A number of physical and chemical changes are shown. Which of these are physical changes?

Physical and chemical changes

Blue copper(II) sulfate crystals are heated in air until they become a white powder. The powder is then left to cool, and after a few days it begins to turn blue. Why does the white powder begin to turn blue?

Physical and chemical changes

Carbon reacts with silver oxide to produce carbon dioxide and silver. Which substance undergoes reduction?

Redox

Base Q is dissolved in water to form aqueous Q. A sample of aqueous Q is then tested using thymolphthalein. Which row states the colour of thymolphthalein in aqueous Q and the ion that causes this colour?

The characteristic properties of acids and bases

Solid calcium hydroxide is mixed with aqueous ammonium chloride and the resulting mixture is heated. A gas is formed. What is the gas called?

The characteristic properties of acids and bases

A gas is placed in a container that keeps its shape, and the container is then closed. Next, the container is heated. Which changes occur?

Solids, liquids and gases

Elements L and M are in the same group of the Periodic Table. Why do L and M show similar chemical properties?

Arrangement of elements

The diagram displays elements W, X, Y and Z in part of the Periodic Table. Which statement correctly describes the elements’ reactivity?

Arrangement of elements

Which three compounds are all insoluble in water?

Elements, compounds and mixtures

18 carat gold is made up of 75% gold and 25% copper by mass. Which statements about 18 carat gold are correct?

Elements, compounds and mixtures

The characteristics of four metals, E, F, G and H, are given. E does not react with cold water, but it does react with steam. F does not react with water or dilute acid, but the oxide of F can be reduced by carbon. The oxide of G cannot be reduced by carbon, yet G reacts vigorously with cold water. H does not react with water or steam, but it does react with dilute acid. What is the order of reactivity of the metals, beginning with the most reactive?

Reactivity series

Four substances, or categories of substances, present in water from a natural source are shown. 1 some metal compounds 2 plastics 3 dissolved oxygen 4 nitrates and phosphates from fertilisers and detergents. Which of the substances present in water from a natural source can be helpful to aquatic life?

Water

Which element is employed to eliminate tastes and odours during treatment of the domestic water supply?

Water

NPK fertilisers are blends of salts that are used to enhance plant growth. Which salt could be used as one ingredient in an NPK fertiliser?

Fertilisers

Plants make glucose through photosynthesis. Which of the following is needed for this process? 1 carbon dioxide 2 oxygen 3 light 4 water

Formulae, functional groups and terminology

Two reactions, M and N, each produce carbon dioxide. $\mathrm{CaCO_3} \xrightarrow{M} \mathrm{CO_2}$ and $\mathrm{CH_4} \xrightarrow{N} \mathrm{CO_2}$. Which kinds of reaction are M and N?

Physical and chemical changes

A crystal of sodium chloride is placed into a beaker containing water. As time passes, the sodium chloride particles spread out uniformly through the water. Which processes take place in this experiment?

Diffusion

The molecular formulae for four compounds are given as $\mathrm{C_2H_2}$, $\mathrm{C_3H_8}$, $\mathrm{C_4H_8}$, $\mathrm{C_5H_{10}}$. How many of these compounds belong to the alkane homologous series?

Alkanes

What type of reaction occurs when pentane reacts with chlorine?

Alkanes

Which bar chart represents the percentage composition of natural gas?

Fuels

Which statement concerning alcohols is correct?

Alcohols

The equation represents the reaction of ethanoic acid with solid P to form Q and hydrogen. $\text{ethanoic acid} + P \rightarrow Q + \text{hydrogen}$. Which row gives the correct identification of P and Q?

The characteristic properties of acids and bases

The diagram displays a single repeat unit of a polymer. Which row states the name of the polymer and the monomer used to produce it?

Polymers

The following properties of a plastic pollutant are given. 1 It conducts electricity poorly. 2 It is unreactive towards water. 3 It resists oxidation. 4 It is of low density. Which of these properties help to explain why this plastic is difficult to remove from the environment?

Polymers

The graph displays the volume of hydrogen formed as time passes during a chemical reaction. A student uses a stop-watch. Which other piece of apparatus is used to obtain the measurements needed to draw this graph?

Experimental design

A student carries out paper chromatography to identify the food dyes in coloured sweet S. Four known food dyes, W, X, Y and Z, are used, with ethanol as the solvent. The chromatogram produced is shown. Which of the following statements are correct?

Chromatography

An aqueous cation reacts with aqueous sodium hydroxide to produce a white precipitate. The precipitate does not dissolve in excess sodium hydroxide. Which aqueous cation is present?

Identification of ions and gases

The electronic structures of two atoms, P and Q, are displayed. P and Q join together to make a compound. What type of bonding is present in the compound, and what is the formula of the compound?

Ions and ionic bonds

A strip of damp red litmus paper is placed into a test-tube containing a gas. The litmus paper becomes white. Which gas is present in the test-tube?

Identification of ions and gases

An ion has the electronic configuration $2,8,8$. Which ion might this be?

Atomic structure and the Periodic Table

The table gives the nucleon number and the number of neutrons in one atom of isotopes W, X, Y and Z. Which statement about W, X, Y and Z is correct?

Isotopes

Which of the following statements about an ionic bond is correct?

Ions and ionic bonds

Which row gives the description of simple molecular compounds?

Simple molecules and covalent bonds

Boron nitride is a compound made from the elements boron and nitrogen. Its structure is similar to that of diamond. Which property is boron nitride likely to have?

Giant covalent structures