Chemistry 2025 · May/June · Paper 12

Consider the following statements. 1 Silicon dioxide has a higher melting point than sulfur dioxide.

Ammonia has a higher boiling point than phosphine, PH Which statements are correct? A both statement 1 and statement 2 B statement 1 only C statement 2 only D neither statement 1 nor statement 2 2 How many neutrons are contained in an atom of iron with a mass number of 60? A 26 B 30 C 34 D 60

The diagram shows a Boltzmann distribution of molecular energies for a gaseous reaction at two different temperatures and two different activation energies. proportion of molecules energy / kJ mol A(1) A(2) Which combination of temperature and activation energy will give the highest reaction rate?A T 1 and E A(1) B T 1 and E A(2) C T 2 and E A(2) D T 2 and E A(1)

The reaction between sulfur dioxide and oxygen has the equation shown. 2SO 2

1.0 mol of SO2 and 1.0 mol of O2 are placed in a closed container and heated to a constant temperature. At this temperature, 0.8 mol of SO3 are present in the equilibrium mixture. Which statement is correct? A The equilibrium partial pressure of SO 2 is greater than the equilibrium partial pressure of O2.B K p has units of mol dm C At a lower temperature, the equilibrium amount of SO 3 is lower than 0.8 mol. D The mole fraction of SO 3 is less than 0.8.

'Red lead' is a red pigment with the formula Pb 3O4. Every formula unit of 'red lead' is the same. Each formula unit contains three lead ions and four oxide ions. Lead has two different oxidation states in 'red lead'. What are the oxidation states of lead in 'red lead'? A +1 and +2 B +1 and +3 C +2 and +4 D +2 and +6

Some standard enthalpy of combustion data are given. substance standard enthalpy change of combustion / kJ mol C

-394 H2

-286 CH3OH

-726 Using these data, what is the enthalpy change of formation of methanol? A -240 kJ mol B -46 kJ mol C 46 kJ mol D 240 kJ mol

Which row is correct? smallest bond angle largest bond angle A H 2O NH 3 BF 3 B BF 3 NH 3 H 2O C NH 3 H 2O BF 3 D H 2O BF 3 NH 3

In the Haber process, the reaction between the two gaseous reactants requires the use of a catalyst that contains a transition element. What is the metal and in which mole ratio do the gases react? metal mole ratio A Fe 1 : 2 B Fe 1 : 3 C V 1 : 2 D V 1 : 3

Aqueous hydrogen peroxide, H 2O2, decomposes into water and oxygen in the presence of a suitable catalyst. of a 0.50 mol dm solution of hydrogen peroxide produced 120 cm of oxygen in 2.0 minutes. The volume of gas was measured at room conditions. What is the average rate of decomposition of hydrogen peroxide during this 2.0 minute period? A 0.000083 mol dm B 0.00083 mol dm C 0.0017 mol dm D 0.10 mol dm

The average intermolecular forces in water are much stronger than the average intermolecular forces in steam. The average intermolecular forces in ice are slightly stronger than the average intermolecular forces in water. Enthalpy changes are associated with the equilibrium processes shown. 2O

Which statements are correct? 3 The intermolecular forces in ice and water are of the same type. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

An experiment is carried out to determine the value of x in hydrated lithium hydroxide, 2O. A sample of the solid is heated in a crucible over a Bunsen flame. Complete dehydration takes place; decomposition does not occur. mass of empty crucible / g = Q 2O / g = R mass of crucible and residue after heating / g = S Which equation gives the correct value of x?-RS-SR )-18( )-23.9( )-18( )-23.9(

A sample of an ideal gas occupies 240 at 37 °C and 100 kPa. How many moles of gas are present in the sample? C 0.0781 D 78.1

Under certain conditions, CCl 4 and H2O react as shown. The activation energy for the reaction is+62 kJ mol CC l Which enthalpy profile diagram best fits this reaction? enthalpy reaction pathCCl + 2H + 4HCl enthalpy reaction pathCCl + 2H + 4HCl enthalpy reaction pathCCl + 2H + 4HCl enthalpy reaction pathCCl + 2H + 4HCl

A helium ion contains two protons, two neutrons and one electron. This helium ion and a proton are passed separately through a uniform electric field. The particles are travelling at the same velocity. Which arrow describes the path of each particle? helium ion proton A 1 2 B 2 1 C 4 5 D 5 4

The skeletal formulae of arginine and lysine are shown. arginine NH O lysine Which row is correct? substance empirical formula M A arginine C 3H7N2O 174 B arginine C 3H8N2O 176 C lysine C 3H7NO 144 D lysine C 3H8NO 146

The oxide and chloride of an element X are separately mixed with water. The two resulting solutions have the same effect on litmus. What could element X be? A Al B Ca C Na D P

Why do the halogens become less volatile as Group 17 is descended? A The halogen-halogen bond energy decreases. B The halogen-halogen bond energy increases. C The number of electrons in each molecule increases. D The van der Waals' forces between molecules become weaker.

Compound M is a white solid. It is the chloride of a Period 3 element. Information about some reactions starting with compound M is given in the table. reaction observation compound M + non-polar solvent colourless solution compound M added a little at a time to water steamy fumes, Q colourless solution, R fumes Q tested with moist blue litmus paper paper turns red solution R + a few drops of NaOH(aq) + excess NaOH(aq) white precipitate dissolves to give a colourless solution What is compound M? A aluminium chloride B magnesium chloride C phosphorus pentachloride D sodium chloride

Which statement about strontium and its compounds is correct? A Strontium hydroxide is more soluble than barium hydroxide. B Strontium sulfate is more soluble than magnesium sulfate. C Strontium nitrate has a lower thermal stability than calcium nitrate. D Strontium is a stronger reducing agent than magnesium.

Sodium bromide is warmed with concentrated sulfuric acid. Which row describes the change in the oxidation number of the sulfur and the role of the bromide ions in the reaction? change in oxidation number of sulfur role of bromide ions A +6 to +4 oxidising agent B +6 to +4 reducing agent C +4 to 0 oxidising agent D +4 to 0 reducing agent

A reaction occurs when ammonium chloride is added to calcium hydroxide. What is the role of the ammonium ions in this reaction? A acid B base C oxidising agent D reducing agent

Elements Y and Z are both in Period 3. Element Y has the smallest atomic radius in Period 3. There are only two elements in Period 3 that have a lower melting point than element Z. Elements Y and Z react together to form compound R. Which compound could be R? A MgCl 2 B MgS C Na 2S D PCl 3 23 1.0 g of each of four different compounds of Group 2 elements are thermally decomposed. The residue in each decomposition is the oxide of the Group 2 element. The volume of gas produced from each reaction is measured at room conditions. Which substance produces the greatest volume of gas? A calcium carbonate B calcium nitrate C strontium carbonate D strontium nitrate

Sulfur dioxide in the atmosphere can form acid rain. This occurs in two steps. 1 oxidation of SO 2 to SO3 2 formation of dilute H 2SO4 Which row identifies the atmospheric catalyst for step 1 and the reagent for step 2? catalyst reagent A O 2 H 2O B O 2 O 2 C NO 2 H 2O D NO 2 O 2

Which statement about the mechanism of an S N1 reaction of a halogenoalkane is correct? A A nucleophile is substituted by an electrophile. B One intermediate is formed from two reacting molecules. C The intermediate is stabilised by adjacent alkyl groups. D The intermediate is uncharged.

The repeat unit of a polymer is shown. H H Three statements about this polymer are listed. 1 Its disposal is hazardous because it produces toxic gases when burned. 2 Two different monomers are used to make this polymer. 3 The monomer for this polymer is 3-chlorobut-2-ene-1-ol. Which statements are correct? A 1 and 2 B 1 and 3 C 1 only D 2 only

Methanoic acid, HCO 2H, has acidic properties similar to those of other carboxylic acids. In addition, it can be oxidised by the same oxidising agents that are capable of oxidising aldehydes. Which pair consists of two compounds that will give the same observations with Fehling's reagent? A HCO 2H and CH3CO2H B HCO 2H and CH3CO2CH3 C HCO 2H and CH3CH2COCH3 D HCO 2H and CH3CH2CHO

Which row gives pentanenitrile as one product? halogenoalkane reagents and conditions heat with HCN heat with KCN using ethanol as solvent heat with HCN heat with KCN using ethanol as solventBrBBrD 29 An ester, R'CO 2R", is hydrolysed in alkaline conditions. R' and R" are different alkyl groups. Which row identifies the two products formed? product 1 product 2 A R'CO 2H R"OH B R'CO 2 - R"OH C R'CO 2H R"O D R'CO 2 - R"O

Which compound cannot be oxidised by acidified potassium dichromate( VI) solution but does react with sodium metal? A (CH 3)3COH B CH 3COCH2CH3 C CH 3CH2CH2CH2OH D CH 3CH2CH(OH)CH3

Butan-2-one reacts with alkaline I 2(aq). An excess of dilute sulfuric acid is then added to the reaction mixture. The organic products of this reaction sequence are triiodomethane and product M. What is product M? A ethanoate ion B ethanoic acid C propanoate ion D propanoic acid

Four reagents are listed. 1 aqueous KCl 2 dilute HCl 3 liquid SOCl 4 solid PCl Which reagents, when added to ethanol, will rapidly produce a gas that turns blue litmus red? A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

Four drops of 1-chlorobutane, 1-bromobutane and 1-iodobutane are put separately into three test-tubes containing 1.0 of aqueous silver nitrate at 60 °C. In each case, a hydrolysis reaction occurs. 2O

+ R-X

R represents C 4H9 and X represents the halogen atom. The rate of formation of cloudiness in the test-tubes is in the order RCl < RBr < RI Why is this? A The bond energy of R-X decreases from RCl to RI. B The first ionisation energy of the halogen decreases from Cl to I. C The solubility of AgX

decreases from AgCl to AgI. D The R-X bond polarity decreases from RCl to RI.

Propanoic acid reacts with LiAl H4 to give organic product P. Methanoic acid reacts with organic product P, in the presence of a few drops of concentrated sulfuric acid, to give organic product Q. What are the skeletal formulae of the two organic products? organic product P organic product Q A OH B OH C O D O

Samples of the gases CH 3Cl and Cl 2 are mixed together and irradiated with ultraviolet light. Which compound is produced by a termination step in the reaction? A HCl B CH 2=CH2 C CH 2Cl CH2Cl D H 2 36 Propan-1-ol, C 3H7OH, is dehydrated by passing its vapour over hot aluminium oxide to give a hydrocarbon. Which structural formula represents the product obtained when the hydrocarbon reacts with bromine? H HH H CCBrH HCCH H HBr CCBrCCH

Alkane S has molecular formula C4H10. S reacts with Cl 2

in the presence of sunlight to produce only two different monochloroalkanes, 4H9Cl. Both of these monochloroalkanes are treated with hot ethanolic KOH. They both produce the same alkene T, and no other organic products. What is produced when T is treated with hot concentrated acidified KMnO A CO 2 and CH3CH2CO2H B CO 2 and CH3COCH3 C HCO 2H and CH3COCH3 D CH 3CO2H only

Including structural isomers and stereoisomers, how many isomers are there of C 2H2Br2? A 2 B 3 C 4 D 5

Which compound exhibits stereoisomerism? A 1,1-dichloropropene B 2,3-dichloropropene C 1,2-dichloropropane D 1,3-dichloropropane

The mass spectrum of CH 3Cl shows a molecular ion peak, M , at the m / e value of 50 with a relative abundance of 18.0%. Other peaks are present in the mass spectrum. What is seen in the mass spectrum at the m / e value of 52? A a peak with relative abundance of 4.5% B a peak with relative abundance of 6.0% C a peak with relative abundance of 18.0% D a peak with relative abundance of 54.0% Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series. Local Examinations Syndicate (UCLES), which is a department of the University of Cambridge. Important values, constants and standards molar gas constant R = 8.31J Kmol C molmol-19 molar volume of gas V m = 22.4 dmmol at s.t.p. (101 kPa and 273 K) m = 24.0 dmmol at room conditions ionic product of water K-14mol specific heat capacity of water c = 4.18 kJ kg (4.18 J g Group The Periodic Table of Elements hydrogen 1.0 He helium 4.0 1213 14 15 16 17 18 3 4 5 6 7 8 9 10 11 123Li lithium 6.9 beryllium 9.0 atomic number atomic symbolKey name relative atomic mass sodium 23.0 magnesium 24.3 potassium 39.1 calcium 40.1 rubidium 85.5 strontium 87.6 caesium 132.9 barium 137.3 francium Ra radium boron 10.8 13 Al aluminium 27.0 31 Ga gallium 69.7 49 In indium 114.8 thallium 204.4 carbon 12.0 14 Si silicon 28.1 32 Ge germanium 72.6 50 Sntin 118.7 82 Pb lead 207.2 titanium 47.9 40 Zr zirconium 91.2 72 Hf hafnium 178.5 rutherfordium vanadium 50.9 41 Nb niobium 92.9 73 Ta tantalum 180.9 105 Db dubnium chromium 52.0 42 Mo molybdenum 95.9 74 W tungsten 183.8 106 Sg seaborgium manganese 54.9 43 Tc technetium rhenium 186.2 107 Bh bohrium iron 55.8 44 Ru ruthenium 101.1 76 Os osmium 190.2 108 Hs hassium Co cobalt 58.9 45 Rh rhodium 102.9 iridium 192.2 109 Mt meitnerium nickel 58.7 46 Pd palladium 106.4 platinum 195.1 11 0 Ds darmstadtium copper 63.5 47 Ag silver 107.9 79 Au gold 197.0 111 Rg roentgenium zinc 65.4 48 Cd cadmium 112.4 80 Hg mercury 200.6 11 2 Cn copernicium 11 4 flerovium 11 6 livermorium nitrogen 14.0 phosphorus 31.0 33 As arsenic 74.9 51 Sb antimony 121.8 bismuth 209.0 oxygen 16.0 sulfur 32.1 34 Se selenium 79.0 52 Te tellurium 127.6 84 Po polonium fluorine 19.0 17 Cl chlorine 35.5 35 Br bromine 79.9 iodine 126.9 Ne neon 20.2 18 Ar argon 39.9 36 Kr krypton 83.8 54 Xe xenon 131.3 86 Rn radon 11 3 nihonium 11 5 moscovium 11 7 tennessine 11 8 oganesson scandium 45.0 yttrium 88.9 57-71 lanthanoids 89-103 actinoids 57La lanthanum 138.9 89 Ac lanthanoids actinoids actinium Ce cerium 140.1 90 Th thorium 232.0 praseodymium 140.9 91 Pa protactinium 231.0 neodymium 144.2 uranium 238.0 promethium neptunium samarium 150.4 94 Pu plutonium europium 152.0 95 Am americium gadolinium 157.3 96 Cm curium terbium 158.9 97 Bk berkelium dysprosium 162.5 californium holmium 164.9 99 Es einsteinium erbium 167.3 100 Fm fermium Tm thulium 168.9 101 Md mendelevium ytterbium 173.1 102 No nobelium lutetium 175.0 lawrencium