Chemistry 2025 · Oct/Nov

What is the electrons in boxes notation for the Fe ion? [Ar] [Ar] [Ar] [Ar] 3d 4s

Which equation has an energy change that is equal to the first ionisation energy of bromine?

The reaction of hydrogen sulfide with sulfur dioxide gives sulfur as one of the products. The two relevant redox equations are shown. 2S(aq) S(s) + 2H

+ 2e 2(aq) + 4H

+ 4e S

+ 2H2O

How many moles of hydrogen sulfide are needed to react with sulfur dioxide to produce 1 mol of sulfur? mol B mol C mol D 2 mol

Which statement is correct? A The relative atomic mass of a Cl atom is 35.5. B The relative molecular mass of O 2 is 16.0. C The relative formula mass of CaCO 3 is 100.1. D The relative isotopic mass of a Mg atom is 24.3.

The bonding between two atoms of nitrogen in an N 2 molecule involves the hybridisation of atomic orbitals to form sp orbitals. Which row is correct? between the nitrogen atoms in N type of orbital which contains the lone pair of electrons on each nitrogen atom in N an sp orbital from one atom overlaps with an sp orbital of the other atom an sp orbital from one atom overlaps with an sp orbital of the other atom an s orbital from one atom overlaps with a p orbital of the other atom an s orbital from one atom overlaps with a p orbital of the other atom

Three bond angles are labelled on the molecule shown. HSCHHHHHH represents a lone pair of electrons What is the order of decreasing size of the bond angles x, y and z? largest smallest A x y z B x z y C y z x D z y x

X and Y are different elements in Period 3. Atoms of X and Y each have only one completely filled orbital in their highest occupied energy sub-shell. Y has a greater first ionisation energy than X. Which row shows the structure and bonding in X and Y? X Y A giant metallic giant metallic B giant metallic simple molecular C giant covalent simple molecular D simple molecular simple molecular

A pure sample of a gas has a density of 2.62 g dm at 101 000 Pa and 25 °C. The gas behaves ideally under these conditions. Which expression gives the M r of the gas? 25 8.31 2.62 0.001 000 101 298 8.31 2.62 0.001 000 101 0.001 000 101 25 8.31 2.62 0.001 000 101 298 8.31 2.62

When 0.47 g of a hydrocarbon is completely burnt in air, the energy released heats 200 g of water from 23.7 °C to 41.0 °C. What is the amount of energy absorbed, in Joules, by the water?

One commercially available 'heat pad' contains iron, activated carbon and water. The 'heat pad' is activated by air. This causes the pad to get hotter. Which statement describes the chemical reaction occurring in the 'heat pad' when it is exposed to air? A The reaction is endothermic and iron gains electrons. B The reaction is endothermic and iron loses electrons. C The reaction is exothermic and iron gains electrons. D The reaction is exothermic and iron loses electrons.

In which substance is the average oxidation number of sulfur the highest?A S 8 B Na 2S4O6 C Na 2S2O3 D SO 2Cl 2

An equilibrium can be represented by the equation shown. P(aq) + Q(aq) 2R(aq) + S(aq) In a certain mixture, of volume 1.0 , the equilibrium concentration of Q is 10 mol dm What will be the new equilibrium concentration of Q if 5.0 mol of pure Q is completely dissolved in the mixture? A 15 mol dm B between 10 mol dm and 15 mol dm C 10 mol dm D between 5.0 mol dm and 10 mol dm

In the Contact process, sulfur dioxide and oxygen react to form sulfur trioxide. In the Haber process, nitrogen and hydrogen react to form ammonia. Which statement about these processes is correct?A K p for the Haber process has no unit. B In the Contact process, the value of K p falls when pressure is increased at constant T. C The Haber process uses a homogeneous catalyst. D When V 2O5 is used in the Contact process, the position of equilibrium is unchanged. 14 20.0 cm of hydrogen peroxide decomposes to water and oxygen in the presence of a suitable catalyst. of oxygen, measured at room conditions, is produced in 5.00 minutes. What is the average rate of decomposition of hydrogen peroxide during this reaction period? mol s mol s mol s mol s

Which reaction pathway diagram shows an endothermic reaction that occurs in two steps and in which the second step of the reaction is likely to be faster than the first? energy extent of reaction energy extent of reaction energy extent of reaction energy extent of reaction

Oxides of nitrogen, NOx, are involved in formation of photochemical smog and acid rain. Which oxides of nitrogen are involved in each of these processes? photochemical smog acid rain NO NO 2 NO NO 2 A 3 3 3 3 B 7 3 7 3 C 3 3 7 3 D 7 3 3 3

Sodium and sulfur react together to form sodium sulfide, Na2S. How do the atomic radius and ionic radius of sodium compare with those of sulfur? atomic radius ionic radius A sulfur is greater sodium is greater B sulfur is greater sulfur is greater C sodium is greater sodium is greater D sodium is greater sulfur is greater

Compound X is an oxide of a Period 3 element. Compound X is a white solid at 25 °C. It reacts with water to form an acidic solution. What is compound X? A aluminium oxide B silicon dioxide C sulfur dioxide D phosphorus( V) oxide

When heated, magnesium nitrate decomposes. Which equation for the thermal decomposition of magnesium nitrate is correct? A Mg(NO B 2Mg(NO D 3Mg(NO

R is the aqueous solution of an ionic compound. 3)2(aq). 3(aq). What is the anion present in compound R? A Cl B SO 4 2- C HCO 3 - D CO 3

In an experiment, 0.600 mol of chlorine gas, Cl 2, is reacted with an excess of hot aqueous sodium hydroxide. One of the products is NaClO3. Which mass of NaCl O3 is formed? A 21.3 g B 44.7 g C 63.9 g D 128 g

X and Y are sodium salts of Group 17 elements. When X reacts with concentrated sulfuric acid, hydrogen sulfide, H 2S, is produced. When Y reacts with concentrated sulfuric acid, there is no change in the oxidation number of the sulfur. Which statement is correct? A Aqueous X reduces aqueous bromine. B Aqueous Y reacts with aqueous silver nitrate to give a precipitate which is insoluble in concentrated aqueous ammonia. C X and Y react separately with concentrated sulfuric acid to produce halogens. D When X reacts with concentrated sulfuric acid, six halide ions are needed to reduce one sulfur atom to H2S.

Element E is in Period 3. It forms a chloride which reacts with a small amount of water to produce a white precipitate and steamy fumes. This precipitate is soluble in NaOH(aq) and in HCl

What is element E? A magnesium B aluminium C silicon D phosphorus

Four reaction mixtures are listed. 1 (NH 4)2SO4(aq) and NaOH 2 NH 4Cl (aq) and Ba(OH)2 3 NH 4Cl (aq) and Na2O 4 (NH 4)3PO4(aq) and HCl Which reaction mixtures produce ammonia as a product? A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 3 and 4 only

Two statements about a molecule of methanal are given. 1 It is planar. Which statements are correct? A both 1 and 2 B 1 only C 2 only D neither 1 nor 2

The structure of disodium cromoglycate is shown. OO CH O ONaOOCH disodium cromoglycate How many chiral centres are there in this molecule? A 0 B 1 C 2 D 3

What is the major product when 2-methylpent-2-ene reacts with hydrogen bromide? A 1-bromo-2-methylpentane B 2-bromo-2-methylpentane C 3-bromo-2-methylpentane D 4-bromo-2-methylpentane

Pent-2-ene is reacted with cold, dilute, acidified manganate(VII) ions. What is the major product? A CH 3CH2CH(OH)CH(OH)CH 3 B CH 3CH2COCOCH 3 C a mixture of CH 3CH2CH(OH)CH2CH3 and CH3CH2CH2CH(OH)CH3 D CH 3CH2COOH and CH3COOH

Limonene is an oil formed in the peel of citrus fruits. limonene Which product is formed when an excess of bromine, Br 2

, reacts with limonene at room temperature in the dark? CCH BrCH

Which reaction mixture produces a nitrile? A halogenoalkane with KCN in ethanol B halogenoalkane with NH 3 in ethanol C ketone with 2,4-DNPH D carboxylic acid with NH 3 in water

Which reaction is classified as SN1? A the reaction of 1-chloropropane with ammonia in ethanol B the reaction of 1-chloropropane with potassium hydroxide in ethanol C the reaction of 2-chloro-2-methylpropane with potassium cyanide in ethanol D the reaction of 2-chloro-2-methylpropane with potassium hydroxide in ethanol

Which reaction mixture produces a primary alcohol as the major product? A propanone with NaBH B propene with steam in the presence of H 3PO4 C butanoic acid with LiAl D ethene with hot concentrated acidified KMnO 33 HOCH 2CHO is heated under reflux with an excess of acidified K2Cr2O7 until there is no further reaction. What is the final product of this reaction? A HOOCCHO B HOCH 2COOH C HOOCCOOH D HOOCCH 2COOH

An organometallic lithium compound, RLi, contains the nucleophile R 3CH2Li reacts with pentan-2-one. The mechanism is nucleophilic addition. The first step produces an anion which is then protonated to form the final product. Which organic product is formed?

The structure of a naturally occurring compound, Q, is shown. compound Q Compound Q is heated under reflux with an excess of acidified KMnO Organic product R is formed. Which row is correct? results of tests with compound Q results of tests with organic product R A orange precipitate with 2,4-DNPH and no reaction with alkaline I 2(aq) yellow precipitate with alkaline I 2(aq) and no reaction with Fehling's reagent red precipitate with Fehling's reagent and no reaction with alkaline I 2(aq) orange precipitate with 2,4-DNPH and no reaction with alkaline I 2(aq) yellow precipitate with alkaline I 2(aq) and orange precipitate with 2,4-DNPH no reaction with alkaline I 2(aq) and no reaction with Fehling's reagent yellow precipitate with alkaline I 2(aq) and red precipitate with Fehling's reagent yellow precipitate with alkaline I 2(aq) and orange precipitate with 2,4-DNPH

Which organic starting material could be used in a single reaction to produce propanoic acid? A ethanenitrile B propan-2-ol C propanal D propyl ethanoate

In four separate reactions, W, X, Y and Z, 1 mol of an organic compound reacts with an excess of a reagent. organic compound reagent W (CH 2COOH)2 Na X CH 3CH(OH)CH2COOH Na 2CO3 Y CH 3CH(OH)CH2COOH NaOH Z CH(OH)(COOH)CH 2COOH Na The volume of any gas produced is collected and measured. All gas volumes are measured at the same temperature and pressure. What is the order of the reactions from greatest total volume of gas collected to least total volume of gas collected? greatest volume least volume A W Y Z X B W Z Y X C Z W X Y D Z X W Y

Butylamine can be produced by the reaction of butanenitrile with hydrogen in the presence of a suitable catalyst. Which volume of hydrogen, measured at room conditions, is required to react completely with 0.500 g of butanenitrile? A 145 B 174 cm C 289 cm D 348 cm

A section of an addition polymer is shown. CCH Which monomer is used to make this polymer?

The purity of a compound can be determined using infrared spectroscopy. The table gives the characteristic infrared absorption frequencies for some selected bonds. bond functional groups containing the bond characteristic infrared absorption range (in wavenumbers) / cm C-O hydroxy, ester 1040-1300 C=O amide carbonyl, carboxyl ester C=C aromatic compound, alkene 1500-1680 C-H alkane 2850-2950 O-H carboxyl hydroxy N-H amine, amide 3300-3500 Propan-2-ol is made by hydration of propene. A sample of the product is obtained. Which feature of the infrared spectrum of the product would show that no propene remains in the product? A absorption in the 2900 region B strong absorption below 1000 C the lack of absorption at or near 1250 D the lack of absorption at or near 1550 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 34567891011123Li 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