Cambridge Past Paper Questions
Browse 23,045questions from 25 years of O-Level & A-Level exams. Click any question to practice.
Which conversion involves a reduction of chromium?
The equilibrium N2(g) + O2(g) ⇌ 2NO(g) ΔΗ= +180 kJ mol-1 contributes to a series of reactions producing photochemical smog. Which factors would aff...
PCl5 dissociates as follows. PCl5(g) → PCl3(g) + Cl2(g) The extent of dissociation is 13% at 160°C and 100% at 300°C. Which pair of statements abou...
Four reactions of the type shown are studied at the same temperature. X(g) + Y(g) → Z(g) Which is the correct reaction pathway diagram for the reac...
The following graph shows the variation of a property of the first 20 elements in the Periodic Table with the atomic number of the element. [Figure...
Which statement correctly describes what happens when silicon tetrachloride is added to water?
Which graph correctly describes a trend found in the halogen group? [X represents a halogen atom.]
During electrolysis of brine in a diaphragm cell, chlorine, hydrogen and sodium hydroxide are produced. What is the molar ratio of these products? ...
When sulfur trioxide is manufactured from sulfur dioxide and oxygen, using the Contact process, which condition affects the value of the equilibriu...
Most modern cars are fitted with three-way catalytic converters in the exhaust system. Which three gases are removed by such a catalytic converter?
In an historically famous experiment Wöhler heated 'inorganic' ammonium cyanate in the absence of air. The only product of the reaction was 'organi...
The drug cortisone has the formula shown. [Figure 19.1] In addition to those chiral centres marked by an asterisk (*), how many other chiral centre...
The presence of 11-cis retinal, C20H28O, in cells in the eye is important for vision. The structure of retinal includes an aldehyde group, a cycloh...
The following diagram represents the structure of a possible polymer. [Figure 22.1] By which method might this polymer be made?
Sorbic acid is used as a food preservative because it kills fungi and moulds. [Figure 23.1] Sorbic acid will react with • hydrogen in the presence ...
Bromine reacts with ethene to form 1,2-dibromoethane. What is the correct description of the organic intermediate in this reaction?
Which equation represents a valid propagation step in the free radical reaction between ethane and chlorine?
The naturally-occurring molecule civetone is found in a gland of the African civet cat and has been used in perfumery. [Figure 26.1] With which rea...
Cyanohydrins can be made from carbonyl compounds by generating CN⁻ ions from HCN in the presence of a weak base. [Figure 27.1] In a similar reactio...
The characteristic odour of rum is attributed to the compound 2-ethyl-3-methylbutanoic acid. [Figure 28.1] Which compound will produce 2-ethyl-3-me...
The acarid mite releases lardolure to attract other mites to a host. This chemical can be destroyed by hydrolysis with acid. [Figure 29.1] A simpli...
An element X consists of four isotopes. The mass spectrum of X is shown in the diagram. [Figure 30.1] What is the relative atomic mass of X?
Which physical properties are due to hydrogen bonding between water molecules? 1 Water has a higher boiling point than H2S. 2 Ice floats on water. ...
Which equilibria, in which all species are gaseous, would have equilibrium constants, Kp, with no units? 1 sulfur dioxide and oxygen in equilibrium...
Why does a mixture of hydrogen gas and bromine gas react together faster at a temperature of 500 K than it does at a temperature of 400 K? 1 A high...
A farmer added lime to damp soil, followed by the nitrogenous fertiliser ammonium sulfate. A chemical reaction occurred in the soil. Which substanc...
Which statements about the reaction of solid sodium bromide with concentrated sulfuric acid are correct? 1 Hydrogen bromide is a product of the rea...
Which statements are true for an SN2 reaction? 1 One bond is broken as another bond is formed. 2 The formation of a transition state involves the c...
The chlorine free radical takes part in the destruction of the ozone layer. Which statements about this free radical are correct? 1 It is formed by...
The diagram shows an experiment. [Figure 38.1] Which processes could be demonstrated by using the above apparatus? 1 the oxidation of ethanol (the ...
A compound has a relative molecular mass of 88 and its molecule contains only four carbon atoms. What could this compound be? 1 a saturated non-cyc...
A monomer undergoes addition polymerisation. A 1 mol sample of the monomer is completely polymerised. How many moles of polymer might, theoreticall...
The ability of an atom in a covalent bond to attract electrons to itself is called its electronegativity. The greater the difference between the el...
Which diagram correctly represents the Boltzmann distribution of molecular energies at two temperatures T₁ and T₂, where T₁ = 300K and T₂ = 310K?
The table gives the radii, in pm, of some ions. [1 pm = 10⁻¹²m] ion radii Na⁺ 102 Mg²⁺ 72 Cs⁺ 167 Cl⁻ 181 O²⁻ 140 Caesium chloride, CsCl, has a dif...
Methanol may be prepared by the reaction between carbon monoxide and hydrogen. CO(g) + 2H₂(g) → CH₃OH(g) The relevant average bond energies are giv...
The reaction pathway diagram below illustrates the energies of reactants, products and the transition state of a reaction. [Figure showing reaction...
Flask X contains 5 dm³ of helium at 12 kPa pressure and flask Y contains 10 dm³ of neon at 6 kPa pressure. If the flasks are connected at constant ...
Use of the Data Booklet is relevant to this question. The enthalpy change of formation, ∆H_f, of hydrated calcium ions is the enthalpy change of th...
The following equilibrium is set up in a mixture of concentrated nitric and sulfuric acids. HNO₃ + H₂SO₄ ⇌ H₂NO₃⁺ + HSO₄⁻ Which row correctly descr...
Which molecule or structure does not contain three atoms bonded at an angle between 109° and 110°?
A dimer, X, is stable when solid but a dynamic equilibrium is set up in solution. X(aq) ⇌ 2Y(aq) A solution of X has an initial concentration of 0....
Equimolar quantities of magnesium carbonate and strontium carbonate are separately heated to bring about complete thermal decomposition. The minimu...
In aqueous solution, the acid HIO disproportionates according to the following equation where m, n, p and q are simple whole numbers in their lowes...
Use of the Data Booklet is relevant to this question. Which mass of solid residue can be obtained from the thermal decomposition of 4.10 g of anhyd...
Which statement explains the observation that magnesium hydroxide dissolves in aqueous ammonium chloride, but not in aqueous sodium chloride?
What happens when chlorine is bubbled through aqueous potassium iodide?
Strontium metal can be obtained by the electrolysis of molten strontium bromide, SrBr₂, using the apparatus shown in the diagram. [Figure showing e...
Which statement about bromine is correct?
Concentrated sulfuric acid reacts with both solid sodium chloride at room temperature and with solid sodium iodide at room temperature. Which row c...