Chemistry 2021 Oct/Nov Paper 12 | Past Paper

Q1

Short Answer 1 mark

Compound X consists of 40.0% carbon, 6.7% hydrogen and 53.3% oxygen by mass. What is the empirical formula of compound X? A CH 2O B C 2H2O C C 2H4O D CHO

Q2

MCQ 1 mark

Which statement is correct? A 1.0 atoms. B 4.0 atoms. C 16 atoms. D 44 atoms. Technetium (Tc) is a second row transition element that does not occur naturally on Earth. One of its isotopes has 56 neutrons. What is the nucleon number of this isotope? A 43 B 56 C 99 D 112

A

1.0

B

4.0

C

16

D

44

A

43 B 56 C 99 D 112

Q4

MCQ 1 mark

Which atom has more unpaired electrons than paired electrons in orbitals of principal quantum number 2? A carbon B nitrogen C oxygen D fluorine

A

carbon

B

nitrogen

C

oxygen

D

fluorine

Q5

MCQ 1 mark

Atom X is the central atom in a molecule. In this molecule, atom X has four pairs of valence electrons in its outer shell. The four pairs of valence electrons include at least one bond pair and at least one lone pair. What could be a possible shape for the molecule? A linear B non-linear C trigonal bipyramidal D trigonal planar

A

linear

B

non-linear

C

trigonal bipyramidal

D

trigonal planar

Q6

Short Answer 1 mark

Which molecule has the largest overall dipole? Cl Cl Cl ClA B OC O

Q7

MCQ 1 mark

The strength of hydrogen bonding increases as the electronegativity of the element bonded to hydrogen increases. Some information for a range of hydrides is given. hydride boiling point PH3 185 HCl 188 HF 293 H2O 373 Which statement and reason about these hydrides is correct? A The boiling point of PH 3 is much lower than the boiling point of H2O because PH3 does not form hydrogen bonds or instantaneous dipole-induced dipole forces between its molecules. B The boiling point of HF is higher than the boiling point of HCl because the bond energy of H-F is greater than the bond energy of H-Cl. C The boiling point of H 2O is higher than the boiling point of HF because each hydrogen bond between the H 2O molecules is stronger than each hydrogen bond between HF molecules. D The boiling points of PH 3 and HCl are similar because the molecules of PH 3 and HCl have the same number of electrons and similar intermolecular forces.

A

The boiling point of PH

B

The boiling point of HF is higher than the boiling point of HCl because the bond energy of

C

The boiling point of H

D

The boiling points of PH

Q8

MCQ 1 mark

The general gas equation can be used to calculate the value of the M r of a gas. For a sample of a gas of mass m grams, which expression will give the value of MA Mr =mRT B M r = pVRT C M r =mpV D M r =mRT

B

M r =

C

M r =mpV

D

M r =mRT

Q9

Short Answer 1 mark

The equation for the formation of ammonium chloride is shown. 3

Q9(g)

Short Answer 1 mark

+ HCl

Q9(g)

Short Answer 1 mark

Which diagram shows the correctly labelled reaction pathway diagram for the decomposition of ammonium chloride? energy progress of reaction + HCl energy progress of reaction + HCl energy progress of reaction + HCl energy progress of reaction + HCl

Q10

Short Answer 1 mark

In a catalytic converter in the exhaust system of a car, carbon monoxide is oxidised to carbon dioxide, and nitrogen monoxide is reduced to nitrogen. What are the changes in oxidation number of carbon and nitrogen in these two processes? carbon nitrogen A -2 +2 B -1 +1 C +1 -1 D +2 -2 11 NO and NO 2 are both present in the lower atmosphere as pollutants. The reaction sequence shows the production of ozone from oxygen in the lower atmosphere. This sequence repeats many times. NO

Q10(g)

Short Answer 1 mark

+ Which statement about this reaction sequence is correct? A NO is acting as a catalyst, but NO 2 is not acting as a catalyst. B NO 2 is acting as a catalyst, but NO is not acting as a catalyst. C Neither NO nor NO 2 are acting as catalysts. D Both NO and NO 2 are acting as catalysts.

Q12

MCQ 1 mark

A mixture of two Period 3 oxides are added to water. A solution forms with a pH of just below 7. What could be the constituents of the mixture? A Al 2O3 and MgO B Na 2O and MgO C Na 2O and P4O10 D SO 3 and P4O10

A

mixture of two Period 3 oxides are added to water. A solution forms with a pH of just below 7.

A

Al

B

Na

C

Na

D

SO

Q13

MCQ 1 mark

Which statement about the compounds of the Group 2 metals is correct? A Barium carbonate is less thermally stable than strontium carbonate. B Barium sulfate is less soluble than magnesium sulfate. C Calcium hydroxide is less soluble than magnesium hydroxide. D Calcium nitrate is more thermally stable than strontium nitrate. 14 A 0.005 mol sample of anhydrous calcium carbonate is completely thermally decomposed to give of gas. In a separate experiment carried out under the same conditions, a 0.005 mol sample of anhydrous calcium nitrate is completely thermally decomposed. The volume of gaseous products is measured. What total volume of gaseous products is produced from the calcium nitrate? A 50 B 100 cm C 200 cm D 250 cm

A

Barium carbonate is less thermally stable than strontium carbonate.

B

Barium sulfate is less soluble than magnesium sulfate.

C

Calcium hydroxide is less soluble than magnesium hydroxide.

D

Calcium nitrate is more thermally stable than strontium nitrate.

A

50

B

100 cm

C

200 cm

D

250 cm

Q15

MCQ 1 mark

Redox reactions are common in the chemistry of Group 17 elements. Which statement is correct? A Br ions will reduce Cl 2 but not I 2. B Cl 2 will oxidise Br ions but not I ions.C F 2 is the weakest oxidising agent out of F2, Cl 2, Br2 and I 2.D I ions are the weakest reducing agent out of F , Cl , Br and I

A

Br

B

Cl

Q16

Short Answer 1 mark

Silver chloride and silver iodide form equilibria when added to water. AgC l

Q16(aq)

Short Answer 1 mark

K c = K 1 Ag I(s)

Q16(aq)

Short Answer 1 mark

K c = K 2 Each equilibrium position lies well to the left. Silver iodide will not dissolve in aqueous ammonia. Silver chloride will dissolve in aqueous ammonia. Another equilibrium is formed.

Q16(aq)

MCQ 1 mark

+ 2NH3(aq) Ag(NH3)2 +(aq) K c = K 3 The position of this equilibrium lies to the right. What is the order of magnitude for these three equilibrium constants? smallest largest A K 3 K 2 K 1 B K 3 K 1 K 2 C K 2 K 1 K 3 D K 1 K 2 K 3

A

K 3 K 2 K 1

B

K 3 K 1 K 2

C

K 2 K 1 K 3

D

K 1 K 2 K 3

Q17

Short Answer 1 mark

X is the ion of a metal which burns with a red flame. Y is an ion that reacts with concentrated H 2SO4 to produce H2S. What could be the formula of a compound containing X and Y? A BaBr 2 B BaI 2 C SrBr 2 D SrI 2

Q18

MCQ 1 mark

Oxides of nitrogen are present in the environment due to natural and man-made sources. Which row is correct? natural source of nitrogen oxides man-made source of nitrogen oxides A electrical discharges in the atmosphere internal combustion engines B electrical discharges in the atmosphere as a by-product of the Haber process C decomposition of dead plants in rivers internal combustion engines D decomposition of dead plants in rivers as a by-product of the Haber process

A

electrical discharges in the atmosphere internal combustion engines

B

electrical discharges in the atmosphere as a by-product of the Haber process

C

decomposition of dead plants in rivers internal combustion engines

D

decomposition of dead plants in rivers as a by-product of the Haber process

Q19

MCQ 1 mark

Magnesium hydroxide dissolves in aqueous ammonium chloride, but not in aqueous sodium chloride. Which statement explains this observation? A The ionic radius of the NH + ion is similar to that of Mg but not that of Na B NH 4Cl dissociates less fully than NaCl. C The Na and Mg ions have the same number of electrons. D The NH + ion can donate a proton.

A

The ionic radius of the NH

B

NH

C

The Na

D

The NH

Q20

MCQ 1 mark

The formula of hydrocortisone acetate is shown. OCOCH hydrocortisone acetate Which row is correct? number of C atoms in one molecule number of chiral atoms in one molecule A 22 7 B 22 8 C 23 7 D 23 8

A

22 7

B

22 8

C

23 7

D

23 8

Q21

MCQ 1 mark

Bromomethane, CH 3Br, decomposes in the stratosphere forming methyl free radicals and bromine free radicals. Which row correctly describes this decomposition? type of bond fission number of electrons in a bromine free radical A homolytic 35 B heterolytic 35 C homolytic 36 D heterolytic 36

B

heterolytic 35

C

homolytic 36

D

heterolytic 36

Q22

Short Answer 1 mark

Structural and stereoisomerism should be taken into account when answering this question. Y is a gaseous hydrocarbon which decolourises aqueous bromine. It contains no rings. 10.0 g of Y occupies a volume of 3.43 dm under room conditions. How many isomeric structures are possible for Y? A 4 B 5 C 6 D 7

Q23

Short Answer 1 mark

Which equation represents a valid propagation step in the chlorination of ethane?A CB CC CD C

Q24

MCQ 1 mark

Butanoic acid can be made from 1-bromopropane in two stages. stage 1 CH stage 2 CH Which types of reaction are stage 1 and stage 2? stage 1 stage 2 A electrophilic addition hydrolysis B electrophilic addition oxidation C nucleophilic substitution hydrolysis D nucleophilic substitution oxidation

A

electrophilic addition hydrolysis

B

electrophilic addition oxidation

C

nucleophilic substitution hydrolysis

D

nucleophilic substitution oxidation

Q25

MCQ 1 mark

A halogenoalkane has the molecular formula C 5H11Br. The halogenoalkane does not form an alkene when treated with ethanolic sodium hydroxide. What could be the halogenoalkane? A 1-bromo-2-methylbutane B 2-bromo-2-methylbutane C 3-bromopentane D 1-bromo-2,2-dimethylpropane

A

halogenoalkane has the molecular formula C

A

1-bromo-2-methylbutane

B

2-bromo-2-methylbutane

C

3-bromopentane

D

1-bromo-2,2-dimethylpropane

Q26

MCQ 1 mark

Compound P is heated under reflux with an excess of acidified potassium dichromate( VI) to form compound Q. Compound Q has a lower boiling point than compound P. What could be compound P? A 2-methylbutan-1-ol B 2-methylbutan-2-ol C pentan-1-ol D pentan-2-ol

A

2-methylbutan-1-ol

B

2-methylbutan-2-ol

C

pentan-1-ol

D

pentan-2-ol

Q27

Short Answer 1 mark

Structural and stereoisomerism should be taken into account when answering this question. An organic compound, X, is dehydrated by heating with concentrated phosphoric( V) acid. Only two organic products are formed. What could be X? OH OH

Q28

MCQ 1 mark

Which compound produces a precipitate with 2,4-dinitrophenylhydrazine reagent and also with alkaline aqueous iodine? A butan-2-ol B butanal C butanone D pentan-3-one

A

butan-2-ol

B

butanal

C

butanone

D

pentan-3-one

Q29

MCQ 1 mark

Organic compound Z has an alcohol group and a carboxylic acid group. Compound Z reacts with magnesium carbonate to make a salt with a relative formula mass of 230.3. Compound Z does not react with acidified potassium manganate( VII). What could be the identity of compound Z? A 2-hydroxy-2-methylbutanoic acid B 2-hydroxy-2-methylpropanoic acid C 3-hydroxy-2-methylbutanoic acid D 3-hydroxy-2-methylpropanoic acid

A

2-hydroxy-2-methylbutanoic acid

B

2-hydroxy-2-methylpropanoic acid

C

3-hydroxy-2-methylbutanoic acid

D

3-hydroxy-2-methylpropanoic acid

Q30

MCQ 1 mark

The infra-red spectrum of Y is shown. 4000 3000 2000 wavenumber / cm 1500 1000 500 transmittance/ % What could Y be? A CH 3CO2C2H5 B CH 2(OH)CH=CHCH 2OH C CH 3(CH2)2CO2H D CH 2(OH)(CH2)2CHO Section B For each of the questions in this section, one or more of the three numbered statements 1 to 3 may be correct. Decide whether each of the statements is or is not correct (you may find it helpful to put a tick against the statements that you consider to be correct). The responses A to D should be selected on the basis of A B C D 1, 2 and 3are correct 1 and 2 only are correct 2 and 3 only are correct 1 only correct No other combination of statements is used as a correct response. Use of the Data Booklet may be appropriate for some questions.

A

CH

B

CH

C

CH

D

CH

A

B C D

Q31

Short Answer 1 mark

The Boltzmann distribution diagram shows a fixed amount of a gas at two different temperatures, 1 and T 2. 2 activation energy molecular energy, E number of particles with energy, E Which statements correctly describe the features of this diagram? 1 Temperature T 1 is lower than temperature T 2. 2 The shaded area indicates the particles that have sufficient energy to react at T 3 The total area under each curve is the same for both temperatures.

Q32

Short Answer 1 mark

Four solutions, each of concentration 0.1 mol dm , were tested with a pH meter. The results are shown. solution formula of acid or base pH acid 1 CH 3CO2H 4 acid 2 HNO 3 1 base 1 CH 3NH2 11 base 2 NaOH 14 Which statements explain these results? 1 Acid 2 has a lower pH than acid 1 because it is more soluble. 2 Base 2 has a higher concentration of hydroxide ions in solution than base 1. 3 Acid 1 dissociates less than acid 2.

Q33

Short Answer 1 mark

Which reactions are redox reactions? 2 + H2 2 2K 2CrO4 + 2H + H2O 3 CuCO

Q34

Short Answer 1 mark

When the liquid N 2F4 is heated, it decomposes into a single product, X. Which statements are correct? 1 N-F bonds are broken during this decomposition. 2 The enthalpy change when N 2F4 decomposes into X is approximately +160 kJ mol 3 Molecules of X are non-linear.

Q35

Short Answer 1 mark

The following statements compare some properties of the oxides and chlorides of sodium and silicon. Which statements are correct? 1 The melting point of SiCl 4 is higher than the melting point of SiO2. 2 SiCl 4 reacts with water, NaCl does not. 3 The melting point of SiCl 4 is lower than the melting point of NaCl. The responses A to D should be selected on the basis of A B C D 1, 2 and 3are correct 1 and 2 only are correct 2 and 3 only are correct 1 only correct No other combination of statements is used as a correct response.

Q36

Short Answer 1 mark

Which statements about ammonium chloride are correct? 1 It reacts with hot aqueous sodium hydroxide to produce an alkaline gas. 2 In solution, it reacts with aqueous silver nitrate to produce a white precipitate. 3 When solid, it reacts with concentrated sulfuric acid to produce chlorine.

Q37

Short Answer 1 mark

What is the same for a pair of optical isomers? 1 their empirical formula 2 their functional groups 3 their structural formula

Q38

Short Answer 1 mark

Which of the molecular formulae represent at least one compound that can undergo addition polymerisation? 1 C4H8 2 C 2H3Cl 3 C 3H6O

Q39

Short Answer 1 mark

Which of the reactions give products containing a chiral centre? 1 CH 2(OH)COCO2H + an excess of HCN 2 CH 2(OH)COCO2H + an excess of NaBH4 3 CH 2(OH)COCO2H + an excess of LiAl H4

Q40

Short Answer 1 mark

Ethyl butanoate is heated with a dilute aqueous solution of sodium hydroxide. Which substances are products of this reaction? 1 sodium butanoate 2 water 3 sodium ethanoate 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. Cambridge Local Examinations Syndicate (UCLES), which itself is a department of the University of Cambridge.

Board	CAIE
Level	A Level
Subject	Chemistry
Code	`9701`
Year	2021
Session	Oct/Nov
Paper No.	Paper 12
Q&A	43 questions

Chemistry 2021 · Oct/Nov · Paper 12

Questions & Model Answers 43 Qs

Paper Details