Cambridge A Level Chemistry 9701 — 2021 May/June Paper 1 · Variant 3

Question 1

1 Compound X is an organic compound that contains 30.6% carbon, 3.8% hydrogen, 20.4% oxygen and 45.2% chlorine by mass. What is the empirical formula of X? A C2H3OCl B C2H4OCl C C3H4OCl D C4H3O2Cl 2

Accepted Answer

A

Question 2

2 A sample of propane, C3H8, with a mass of 9.61 g is completely combusted in an excess of oxygen under room conditions. Which volume of carbon dioxide gas is produced? A 4.89 dm3 B 5.24 dm3 C 14.7 dm3 D 15.7 dm3

Accepted Answer

D

Question 3

3 Which atom has the same number of electrons as an ammonium ion? A Mg B Na C Ne D O

Accepted Answer

C

Question 4

4 Ethanal reacts with hydroxylamine, NH2OH, to form the molecule shown. H H y z H C C N O H x H What is the order of increasing bond angle in this structure from smallest to largest? A z, x, y B y, z, x C x, z, y D z, y, x

Accepted Answer

A

Question 5

5 Descriptions of the bonding in three substances are given. substance 1 strong covalent bonds between atoms, permanent dipole-dipole attractions between molecules substance 2 strong covalent bonds between atoms, weak forces between molecules substance 3 strong covalent bonds between atoms, hydrogen bonding between molecules Which compounds could be substances 1, 2 and 3? substance 1 substance 2 substance 3 A CH3OH Al 2Cl 6 CH2Cl 2 B Al 2Cl 6 CH2Cl 2 CH4 C CH2Cl 2 CH4 CH3OH D CH4 CH3OH H2O

Accepted Answer

C

Question 6

6 Which type of bonding is never found in elements? A covalent B ionic C metallic D van der Waals’ forces

Accepted Answer

B

Question 7

7 Using the information in the table, what is the enthalpy change, q, for the reaction described? Cs+(g)  +  Br –(g)    CsBr(s) ∆H = q kJ mol–1 standard value enthalpy change / kJ mol–1  H o CsBr(s) +25.9 sol  H o Cs+(g) –276 hyd  H o Br –(g) –335 hyd A –636.9 B –585.1 C +585.1 D +636.9

Accepted Answer

A

Question 8

8 Which enthalpy change is indicated by X in the enthalpy cycle shown? C(s)  +  2H2(g)  +  2O2(g) CH4(g) CO2(g)  +  X CH4(g) CH4(g)  +  2O2(g) CO2(g)  +  2H2O(l) A – 4  the enthalpy of combustion of hydrogen B + 4  the enthalpy of combustion of hydrogen C – 2  the enthalpy of formation of water D + 2  the enthalpy of formation of water

Accepted Answer

D

Question 9

9 Copper dissolves in dilute nitric acid producing a blue solution of Cu(NO3)2, water and nitrogen(II) oxide as the only products. How many moles of acid react with three moles of copper in the balanced equation? A 2 B 4 C 6 D 8

Accepted Answer

D

Question 10

10 Nitrogen reacts with hydrogen to produce ammonia. N2(g)  +  3H2(g) 2NH3(g) A mixture of 2.00 mol of nitrogen, 6.00 mol of hydrogen and 2.40 mol of ammonia is allowed to reach equilibrium in a sealed vessel of volume 1 dm3. It is found that 2.32 mol of nitrogen were present in the equilibrium mixture. Which expression will give the value of Kc? ( 1 . 76 ) 2 A ( 2 . 32 )( 6 . 96 ) 3 ( 1 . 76 ) 2 B ( 2 . 32 )( 6 . 32 ) 3 ( 2 . 08 ) 2 C ( 2 . 32 )( 6 . 32 ) 3 ( 2 . 40 ) 2 D ( 2 . 32 )( 6 . 00 ) 3

Accepted Answer

A

Question 11

11 Nitric acid is produced by oxidising ammonia. The first step is to react ammonia with oxygen in the presence of a catalyst to form nitrogen monoxide. 4NH3(g)  +  5O2(g) 4NO(g)  +  6H2O(g) H = –1636 kJ mol–1 Which set of conditions will produce the greatest yield of nitrogen monoxide at equilibrium? temperature pressure A high high B high low C low high D low low

Accepted Answer

D

Question 12

12 The height of the peak of the curve in a Boltzmann distribution represents the number of molecules that have the most probable energy. A sample of gas has its temperature decreased without changing the number of molecules present. Which statement correctly describes a feature of the Boltzmann distribution for the gas when the temperature decreases? A The value of the most probable energy would stay the same. B The number of molecules with the most probable energy would increase. C The area under the molecular energy distribution curve would decrease. D The number of molecules at the very high energy end of the distribution would stay the same.

Accepted Answer

B

Question 13

13 Ammonia exists as simple covalent molecules, NH3. Ammonia can react with suitable reagents to form products containing ammonium ions, NH4 +. Ammonia can also react with suitable reagents to form products containing amide ions, NH2 –. Which of these nitrogen-containing species are present in an aqueous solution of ammonia? A ammonia molecules and amide ions B ammonia molecules and ammonium ions C ammonia molecules only D ammonium ions only

Accepted Answer

B

Question 14

14 Which problem can result if too much NH4NO3 is applied to crops by farmers? A Not all the NH4NO3 is used by plants and the excess makes the soil alkaline. B Rain washes some of the NH4NO3 into rivers where it forms a precipitate. C Some of the NH4NO3 dissolves in groundwater which may eventually be used for drinking. D Ammonia is produced; this lowers the pH of the soil.

Accepted Answer

C

Question 15

15 When descending Group 17 from chlorine to iodine, which statement is correct? A The hydrides become less thermally stable as they become weaker reducing agents. B The hydrides become more thermally stable as the reactivity of the elements decreases. C The volatility of the elements decreases as the van der Waals’ forces increase. D The volatility of the elements increases as the size of the molecules increases.

Accepted Answer

C

Question 16

16 A powder is known to be either a single sodium halide or a mixture of two sodium halides. A sample of the powder was dissolved in water. Aqueous silver nitrate was added, and a pale yellow precipitate was formed. When concentrated aqueous ammonia was then added, this precipitate partly dissolved leaving a darker yellow precipitate. What could the powder be? A sodium bromide only B sodium iodide only C a mixture of sodium chloride and sodium bromide D a mixture of sodium chloride and sodium iodide

Accepted Answer

D

Question 17

17 Which statement is correct? A Doctors can use the very insoluble MgSO4 to investigate the digestive system. B Farmers can lower the pH of soil by spreading CaCO3 on it. C Students can test a solution for SO4 2– ions by using Ba(NO3)2(aq) followed by HNO3(aq). D The insoluble hydroxide, Ba(OH)2, can be safely used to lower the acidity of the stomach.

Accepted Answer

C

Question 18

18 A solid, X, was placed in an excess of the liquid Y. A colourless gas was given off and a white precipitate was seen. The precipitate was not X. What could be the identities of X and Y? X Y A BaCO3 H2O B Ca dilute H2SO4 C Mg dilute H2SO4 D SrCO3 dilute HCl

Accepted Answer

B

Question 19

19 Two oxides of Period 3 elements are added separately to water. Both react to form colourless solutions. One solution is alkaline, the other is acidic. What could be the two oxides? A Al 2O3 and SiO2 B Al 2O3 and P4O10 C Na2O and P4O10 D Na2O and SiO2

Accepted Answer

C

Question 20

20 Which compound shows stereoisomerism? A 2-methylbut-2-ene B 2-chloropropan-1-ol C difluorochlorobromomethane D pent-1-ene

Accepted Answer

B

Question 21

21 Two carbon-containing products result from the reaction of alkene Z with a hot, concentrated, acidified solution of potassium manganate(VII). One product forms an orange precipitate with 2,4-dinitrophenylhydrazine reagent. The other product is a gas which gives a white precipitate with aqueous calcium hydroxide. Which alkene could be alkene Z? A but-2-ene B 2-methylpropene C 2-methylbut-2-ene D propene

Accepted Answer

B

Question 22

22 What is the correct mechanism for the addition of hydrogen bromide to ethene?

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H H H 4H H H
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ato
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H H H H H H
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H wa Br H H oH
Bro
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H H H H H H
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D —=C H—C—C* H—C—C—Br
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Ho

Accepted Answer

B

Question 23

23 Halogenoalkanes react with nucleophiles such as OH–. Which pair of halogenoalkanes both react via an SN1 mechanism? A B Br Cl and and Cl Br C D Br and and Br Cl Br

Accepted Answer

A

Question 24

24 A mixture of ethanol and methanol is burned in oxygen to produce 35 cm3 of CO2 and 55 cm3 of H2O. Complete combustion occurs and the volumes of both products are measured at 101 kPa and 120 C. What is the molar ratio, ethanol : methanol, in the mixture? A 1 : 3 B 2 : 3 C 3 : 2 D 3 : 1

Accepted Answer

D

Question 25

25 Two reactions are shown. Only one product is identified in each reaction. ethanol  +  acidified Cr2O7 2–    ethanal ethanol  +  sodium    sodium ethoxide Which statement about these reactions is correct? A The formations of both ethanal and sodium ethoxide are redox reactions. B The formations of both ethanal and sodium ethoxide result in colour changes. C The formation of ethanal is catalysed by potassium dichromate. D The formation of sodium ethoxide is a dehydration reaction.

Accepted Answer

A

Question 26

26 The skeletal formulae of three compounds are shown. R S T OH O O O O Which compounds will give a positive test with 2,4-dinitrophenylhydrazine reagent? A R only B R and S only C S and T only D R, S and T

Accepted Answer

A

Question 27

27 The diagram shows the structure of a compound formed by the reaction of HCN with a carbonyl compound, X. C4H9 H3C C CN OH What is the mechanism of this reaction and what is the functional group in X? mechanism of reaction functional group in X A electrophilic addition aldehyde B electrophilic addition ketone C nucleophilic addition aldehyde D nucleophilic addition ketone

Accepted Answer

D

Question 28

28 Compound Y is treated with a single reagent under suitable conditions. 2-methylbutanoic acid is produced. What could compound Y be? A pentan-2-one B 2-methylbutan-2-ol C 2-methylbutanenitrile D methylpropanenitrile

Accepted Answer

C

Question 29

29 Two reactions are shown. LiAl H4 (CH3)2CHCO2H alcohol P hydrolysis CH3CO2CH(CH3)2 alcohol Q  +  acid R To which classes of alcohol do P and Q belong? P Q A primary primary B primary secondary C secondary primary D secondary secondary

Accepted Answer

B

Question 30

30 The infra-red spectrum of molecule Z is shown. 100 transmittance / % 50 0 4000 3000 2000 1500 1000 500 wavenumber / cm–1 What could be the identity of Z? A B HO OH O O HO O O O C D O O O O O O

Accepted Answer

D

Question 31

31 Which statements about first ionisation energies are correct? 1 They are always endothermic. 2 They decrease down Group 2. 3 They decrease across Period 3.

Accepted Answer

B

Question 32

32 The equation shows the decomposition of three moles of an ion containing chromium in an acid solution. 3CrO4 3–(aq)  +  8H+(aq)    2CrO4 2–(aq)  +  Cr3+(aq)  +  4H2O(l) Which statements are correct? 1 One mole of CrO4 3– is reduced. 2 Two moles of CrO4 3– are oxidised. 3 Three moles of electrons are transferred.

Accepted Answer

B

Question 33

33 Disaccharides are hydrolysed in slightly acidic solutions. This reaction is very slow. A biological catalyst is added to a slightly acidic mixture of three disaccharides, sucrose, maltose and lactose. The hydrolysis reaction remains slow for sucrose and maltose but is now much faster for lactose. Which statements about the catalyst are correct? 1 The catalyst increases the activation energy of all three hydrolysis reactions. 2 The catalyst shows specificity. 3 The hydrolysis of lactose using a catalyst has a different mechanism to the hydrolysis of lactose without a catalyst.

Accepted Answer

C

Question 34

34 Element X is a solid under room conditions. It occurs as a contaminant of fossil fuels. Its oxide, Y, is formed when fossil fuels are burned. In the atmosphere, Y can be further oxidised to Z. Which statements about X, Y and Z are correct? 1 Atoms of X have paired p electrons. 2 The atmospheric oxidation of Y to Z is a catalysed reaction. 3 With water, Z forms a strong acid.

Accepted Answer

A

Question 35

35 Which reagents produce a solution of sodium chlorate(V)? 1 chlorine and hot concentrated sodium hydroxide solution 2 chlorine and cold dilute sodium hydroxide solution 3 chlorine dissolved in water at room temperature

Accepted Answer

D

Question 36

36 Which statements help to explain the increase in melting point from sodium to aluminium? 1 The charge on the metal ion increases. 2 There are more delocalised electrons per metal ion. 3 The radius of the metal ion decreases.

Accepted Answer

A

Question 37

37 The diagram shows a molecule of a compound used as a flame retardant. Br Br Br Br Br Br Which statements about this structure are correct? 1 Each brominated C atom is chiral. 2 The molecular formula is C12H20Br6. 3 The C–C–C bond angles are all 120.

Accepted Answer

D

Question 38

38 Bromoethane reacts with NaOH in different ways depending on the solvent used. Which rows about these reactions are correct? solvent used organic product 1 water ethan-1,2-diol 2 ethanol ethene 3 water ethanol

Accepted Answer

C

Question 39

39 Three compounds, X, Y and Z, are shown. X Y Z C2H5COCH3 C2H5CHO CH3CO2H Which statements about X, Y and Z are correct? 1 X reacts with alkaline aqueous iodine. 2 Y reacts with Tollens’ reagent. 3 Z does not react with alkaline aqueous iodine.

Accepted Answer

A

Question 40

40 5-hydroxypentanoic acid is readily converted into the cyclic compound L. L O O Which statements about this reaction are correct? 1 Acidified sodium dichromate(VI) is used as a reagent. 2 A water molecule is produced in the reaction. 3 The reaction can be catalysed by concentrated H2SO4.

Accepted Answer

C

Question paper16 pages

Mark scheme3 pages

Questions as text

Q1 · Compound X is an organic compound that contains 30.6% carbon, 3.8% hydrogen, 20.4% oxygen…

Q2 · A sample of propane, C3H8, with a mass of 9.61 g is completely combusted in an excess of…

Q3 · Which atom has the same number of electrons as an ammonium ion?

Q4 · Ethanal reacts with hydroxylamine, NH2OH, to form the molecule shown

Q5 · Descriptions of the bonding in three substances are given

Q6 · Which type of bonding is never found in elements?

Q7 · Using the information in the table, what is the enthalpy change, q, for the reaction…

Q8 · Which enthalpy change is indicated by X in the enthalpy cycle shown?

Q9 · Copper dissolves in dilute nitric acid producing a blue solution of Cu(NO3)2, water and…

Q10 · Nitrogen reacts with hydrogen to produce ammonia

Q11 · Nitric acid is produced by oxidising ammonia

Q12 · The height of the peak of the curve in a Boltzmann distribution represents the number of…

Q13 · Ammonia exists as simple covalent molecules, NH3

Q14 · Which problem can result if too much NH4NO3 is applied to crops by farmers?

Q15 · When descending Group 17 from chlorine to iodine, which statement is correct?

Q16 · A powder is known to be either a single sodium halide or a mixture of two sodium halides

Q17 · Which statement is correct?

Q18 · A solid, X, was placed in an excess of the liquid Y

Q19 · Two oxides of Period 3 elements are added separately to water

Q20 · Which compound shows stereoisomerism?

Q21 · Two carbon-containing products result from the reaction of alkene Z with a hot…

Q22 · What is the correct mechanism for the addition of hydrogen bromide to ethene?

Q23 · Halogenoalkanes react with nucleophiles such as OH–

Q24 · A mixture of ethanol and methanol is burned in oxygen to produce 35 cm3 of CO2 and 55 cm3…

Q25 · Two reactions are shown

Q26 · The skeletal formulae of three compounds are shown

Q27 · The diagram shows the structure of a compound formed by the reaction of HCN with a…

Q28 · Compound Y is treated with a single reagent under suitable conditions

Q29 · Two reactions are shown

Q30 · The infra-red spectrum of molecule Z is shown

Q31 · Which statements about first ionisation energies are correct?

Q32 · The equation shows the decomposition of three moles of an ion containing chromium in an…

Q33 · Disaccharides are hydrolysed in slightly acidic solutions

Q34 · Element X is a solid under room conditions

Q35 · Which reagents produce a solution of sodium chlorate(V)?

Q36 · Which statements help to explain the increase in melting point from sodium to aluminium?

Q37 · The diagram shows a molecule of a compound used as a flame retardant

Q38 · Bromoethane reacts with NaOH in different ways depending on the solvent used

Q39 · Three compounds, X, Y and Z, are shown

Q40 · 5-hydroxypentanoic acid is readily converted into the cyclic compound L

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