Chemistry 2021 May/June | Past Paper

Q1

MCQ 1 mark

Which statement about the Avogadro constant is correct? A It is the mass of one mole of any element. atoms of any element. C It is the number of atoms in one mole of neon. D It is the number of atoms in 12 g of any element.

A

It is the mass of one mole of any element.

C

It is the number of atoms in one mole of neon.

D

It is the number of atoms in 12

Q2

Short Answer 1 mark

Which equation represents the first ionisation energy of iodine? I2(g) + e

Q2(g)

Short Answer 1 mark

B I(g) + e

Q3

MCQ 1 mark

The structures represent three compounds, each with four carbon atoms per molecule. Which row is correct? lowest boiling point highest boiling point A X Y Z B Y X Z C Z X Y D Z Y X

A

X Y Z

B

Y X Z

C

Z X Y

D

Z Y X

Q4

Short Answer 1 mark

The structural formula of alliin is shown. CSCH HONH HCCHy z alliin What are the approximate bond angles x, y and z in a molecule of alliin? x y z

Q5

Short Answer 1 mark

Flask Q contains 5 of helium at 12 kPa pressure. Flask R contains 10 dm of neon at 6 kPa pressure. If the flasks are connected at constant temperature, what is the final pressure?A 8 kPa B 9 kPa C 10 kPa D 11 kPa

Q6

Short Answer 1 mark

Sodium chloride, water and air represent three states of matter - solid, liquid and gas. Which row is correct? sodium chloride water air particles held in rigid structure can easily be compressed can easily be compressed particles stationary particles move cannot easily be compressed C particles stationary particles stationary particles move resistant to change of shape cannot easily be compressed can easily be compressed

Q7

Short Answer 1 mark

The reaction pathway diagram for the catalysed reaction and the uncatalysed reaction between 2 and H2 is shown. 2

Q7(g)

Short Answer 1 mark

+ 3H2

Q7(g)

Short Answer 1 mark

Which letter represents the activation energy for the first step in the decomposition of NH 3 in the presence of a catalyst? energy reaction pathway

Q8

MCQ 1 mark

Nitrogen and oxygen can react together to form nitrogen monoxide, NO. What is the bond energy of the bond between the atoms in NO? A 630 kJ mol B 810 kJ mol C 1260 kJ mol D 1620 kJ mol

A

630

B

810 kJ mol

C

1260 kJ mol

D

1620 kJ mol

Q9

MCQ 1 mark

The equation for a redox reaction is shown. SnCl Which species is being oxidised in this reaction? A Sn B Cl C Hg D Hg

A

Sn

B

Cl

C

Hg

D

Hg

Q10

Short Answer 1 mark

3.60 moles of hydrogen gas and 2.00 moles of iodine vapour are placed in a reaction vessel which is then sealed and maintained at a constant temperature. The equation for the reaction is shown. 2 + I 2 2HI At equilibrium, 3.20 moles of hydrogen remain. All reactants and products are gaseous. What is the value of K p under these conditions? A 0.0313 B 0.125 C 0.156 D 8.00

Q11

MCQ 1 mark

Two chemicals, X and Y, react together in solution to give product Z. The rate of formation of product Z at the start of the reaction was measured in five experiments, 1-5, using various concentrations of X and Y. The results are shown. experiment number starting concentration of X / mol dm starting concentration of Y / mol dm rate of formation of Z at the start / mol dm 1 0.10 0.10 0.0001 2 0.10 0.20 0.0004 3 0.10 0.40 0.0016 4 0.20 0.10 0.0001 5 0.40 0.10 0.0001 Which statement is correct? A The rate of the reaction is directly proportional to the concentration of reagent X. B The rate of the reaction is directly proportional to the concentration of reagent Y. C The rate of the reaction is not affected by the concentration of reagent X. D The rate of the reaction is not affected by the concentration of reagent Y.

A

The rate of the reaction is directly proportional to the concentration of reagent X.

B

The rate of the reaction is directly proportional to the concentration of reagent Y.

C

The rate of the reaction is not affected by the concentration of reagent X.

D

The rate of the reaction is not affected by the concentration of reagent Y.

Q12

MCQ 1 mark

A sample of SiCl 4 is added to cold water. Which statement describes the mixture formed at the end of the reaction? A acidic solution with no precipitate B acidic solution with white precipitate C neutral solution with no precipitate D neutral solution with white precipitate

A

sample of SiCl

A

acidic solution with no precipitate

B

acidic solution with white precipitate

C

neutral solution with no precipitate

D

neutral solution with white precipitate

Q13

Short Answer 1 mark

L and M are elements in Period 3 of the Periodic Table. Which formula represents a compound of elements L and M? A Al 2S3 B MgS C NaCl D PCl 5

Q14

MCQ 1 mark

A farmer requires a solid compound to raise the pH of the soil in a field from 5.5 to above 6.0. Which compound could the farmer use? A (NH 4)2SO4 B NH 4NO3 C Ca(OH) 2 D Ca(NO 3)2

A

farmer requires a solid compound to raise the pH of the soil in a field from 5.5 to above 6.0.

A

(NH

Q15

MCQ 1 mark

Z is an anhydrous compound of a Group 2 element. When it is heated, Z undergoes thermal decomposition to produce two different gases. Z has relatively low thermal stability compared to other Group 2 compounds containing the same anion as Z. What is compound Z? A barium carbonate B barium nitrate C magnesium carbonate D magnesium nitrate

A

barium carbonate

B

barium nitrate

C

magnesium carbonate

D

magnesium nitrate

Q16

Short Answer 1 mark

Which row gives mixtures that both result in the oxidation of a halide ion? mixture 1 mixture 2 A AgNO 3(aq) and NaCl (aq) concentrated H 2SO4(aq) and HI(aq) B Br 2(aq) and NaCl (aq) concentrated H 2SO4(aq) and HCl (aq) C Cl 2(aq) and NaBr(aq) CH 3CHBrCH3

Q16(l)

Short Answer 1 mark

+ NaOH (ethanolic) D Br 2(aq) and NaI(aq) concentrated H 2SO4(aq) and NaBr

Q17

MCQ 1 mark

Chlorine gas is widely used to treat contaminated water. When chlorine is added to water, which chemical species present is responsible for killing bacteria? A Cl - B Cl C HCl D Cl O

A

Cl

C

HCl D Cl O

Q18

MCQ 1 mark

What is an environmental consequence of the uncontrolled use of nitrate fertilisers? A acid rain B low oxygen levels in streams C ozone depletion D the greenhouse effect

A

acid rain

B

low oxygen levels in streams

C

ozone depletion

D

the greenhouse effect

Q19

Short Answer 1 mark

Ammonia gas, NH 3, and hydrogen sulfide gas, H2S, react together to form the salt ammonium sulfide, (NH 4)2S. Ammonium sulfide dissolves in water to produce an orange alkaline solution. (NH 4)2S(aq) NH3(aq) + NH4SH(aq) The addition of NaOH(aq) to this solution produces a gas, X. The addition of HCl

Q19(aq)

MCQ 1 mark

to a separate portion of this solution produces a gas, Y. X and Y could represent different gases or identical gases. What are the identities of X and Y? X Y A H 2S H 2S B H 2S NH 3 C NH 3 H 2S D NH 3 NH 3

A

H 2S H 2S

B

H 2S NH 3

C

NH 3 H 2S

D

NH 3 NH 3

Q20

Short Answer 1 mark

Compound P is treated with an excess of hydrogen gas in the presence of a nickel catalyst. The product Q is fully saturated. compound P What is the number of chiral carbon atoms in the product Q? A 4 B 5 C 6 D 7

Q21

MCQ 1 mark

Hexadeca-10,12-dien-1-ol is produced by silk moths from hexadecanoic acid in a three-step enzymic process. step 3 step 2 step 1 hexadecanoic acid Which row contains correct descriptions of the three steps? step 1 step 2 step 3 A elimination elimination dehydration B elimination reduction reduction C oxidation elimination oxidation D oxidation oxidation reduction

A

elimination elimination dehydration

B

elimination reduction reduction

C

oxidation elimination oxidation

D

oxidation oxidation reduction

Q22

Short Answer 1 mark

Compound X can be converted into compound Y in a single step. O O compound Y What could be the identity of X? DCBA

Q23

Short Answer 1 mark

Methane and bromine react by free radical substitution. P and Q are involved in the reaction mechanism. P and Q: What could be P and Q? A Br and H B Br and CH 3 C Br and C 2H6 D CH 3 and CH3Br

Q24

MCQ 1 mark

A few drops of 2-bromopropane were placed in a test-tube. An equal volume of aqueous silver nitrate was added. A precipitate was formed. The experiment was repeated with 2-iodopropane. Which row is correct? colour of precipitate from 2-bromopropane + AgNO 3(aq) faster rate of reaction A cream 2-bromopropane + AgNO 3(aq) B yellow 2-bromopropane + AgNO 3(aq) C cream 2-iodopropane + AgNO 3(aq) D yellow 2-iodopropane + AgNO 3(aq)

A

few drops of 2-bromopropane were placed in a test-tube. An equal volume of aqueous

A

cream 2-bromopropane + AgNO 3(aq)

B

yellow 2-bromopropane + AgNO 3(aq)

C

cream 2-iodopropane + AgNO 3(aq)

D

yellow 2-iodopropane + AgNO 3(aq)

Q25

MCQ 1 mark

Sodium methoxide, Na CH3O , reacts with 2-chloro-2-methylpropane in a nucleophilic substitution reaction. The nucleophile is the CH ion. Which row is correct? intermediate or transition state product A (CH 3)3C (CH 3)3COCH3 B (CH 3)3C (CH 3)3CCH2OHC H CC l HOCH 2C(CH3)3D H CC l 3COC(CH3)3

A

(CH 3)3C

B

(CH 3)3C

Q26

MCQ 1 mark

Alcohol X reacts with concentrated sulfuric acid to produce a mixture of products. Two of the products are structural isomers of each other. What could be X? A hexan-2-ol B pentan-1-ol C pentan-3-ol D propan-2-ol

A

hexan-2-ol

B

pentan-1-ol

C

pentan-3-ol

D

propan-2-ol

Q27

MCQ 1 mark

Which reaction will form a strong organic base? A ethanol and acidified sodium dichromate B ethanol and hot aluminium oxide C ethanol and sodium D ethanol and hydrogen chloride

A

ethanol and acidified sodium dichromate

B

ethanol and hot aluminium oxide

C

ethanol and sodium

D

ethanol and hydrogen chloride

Q28

Short Answer 1 mark

Which reaction mechanism for the formation of C2H5CH(OH)(CN) is correct?

Q29

MCQ 1 mark

The synthesis shown may be used for the production of propan-1-ol. step 1 step 2 compound X Which row gives the correct reagents for steps 1 and 2? step 1 step 2 A HCl (aq) H 2 + Ni B HCl (aq) LiA l H4 C NaOH(aq) H 2 + Ni D NaOH(aq) NaBH 4

A

HCl (aq) H 2 + Ni

B

HCl (aq) LiA l H4

C

NaOH(aq) H 2 + Ni

D

NaOH(aq) NaBH 4

Q30

Short Answer 1 mark

The molecular formula of Z is C4H8O. The infra-red spectrum of Z is shown. 4000 3000 2000 wavenumber / cm 1500 1000 500 transmittance/ % What could be Z? ABCD OHOH 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.

Q31

Short Answer 1 mark

In which ions are the number of electrons equal to the number of neutrons?

Q32

Short Answer 1 mark

Compound X is a straight chain hydrocarbon with an M r of 84. What can be determined about X? 1 empirical formula 2 molecular formula 3 whether X contains a C=C bond or not 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.

Q33

Short Answer 1 mark

When a sample of ammonium chloride is warmed it decomposes into ammonia and hydrogen chloride gas. heat cold surface solid ammonium chloride solid ammonium chloride (reformed) When the mixture of hot ammonia and hydrogen chloride gases hit a cold surface, a white solid of ammonium chloride reforms. Which statements are correct? 1 Reaction 1 is in dynamic equilibrium. 2 Reaction 1 is reversible. 3 Reaction 1 is an endothermic reaction.

Q34

Short Answer 1 mark

Hydrogen chloride gas is formed by the reaction shown. What will change the average kinetic energy of the reacting gas particles? 1 increasing the temperature and increasing the concentration of hydrogen 2 cooling the reaction mixture and adding a catalyst 3 adding a catalyst and increasing the concentration of chlorine

Q35

Short Answer 1 mark

Which oxides will cause a change in pH when added to water? 1 CaO 2 Al2O3 3 SiO

Q36

Short Answer 1 mark

Which reaction routes can be used to make a pure sample of barium sulfate? filter, wash and dry1Ba heat in O product product diluteHCl dilute product filter, wash and dry filter, wash and dry 2Ba(NO strong heat in air solid product product an excess of water dilute product 3Ba(OH) diluteHNO product product dilute

Q37

Short Answer 1 mark

Cortisone is a synthetic hormone. cortisone Which classes of alcohol does this molecule contain? 1 primary alcohol 2 secondary alcohol 3 tertiary alcohol

Q38

Short Answer 1 mark

Which changes are commonly involved in the formation of an addition polymer? 3 the change in hybridisation of the orbitals of a carbon atom from sp to sp 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. 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.

Q39

Short Answer 1 mark

Which alcohols can be oxidised to form an organic compound whic h will give coloured precipitates with both 2,4-dinitrophenylhydrazine reagent and alkaline aqueous iodine? OOH

Q40

Short Answer 1 mark

Which mixtures form a carboxylic acid as one of the products? + H

Board	CAIE
Level	A Level
Subject	Chemistry
Code	`9701`
Year	2021
Session	May/June
Q&A	45 questions

Chemistry 2021 · May/June

Questions & Model Answers 45 Qs

Paper Details