CAIE A Level 9701

Chemistry 2020 · May/June

39 Questions Q&A Available

Questions & Model Answers 39 Qs

Short Answer 1 mark

Gallium is an element in Group 13. A sample of gallium is analysed using a mass spectrometer. The mass spectrum produced is shown. % relative abundance mass 6971 60.11% 39.89%

Q1(a)

Short Answer 1 mark

Explain what is meant by the term relative atomic mass.

Q1(b)

Short Answer 2 marks

Calculate the relative atomic mass of gallium in this sample. Give your answer to 4 significant figures. Show your working. relative atomic mass =

Q1(c)

Short Answer 2 marks

Complete the table which describes a gaseous atom of gallium. isotope nucleon number total number of electrons in lowest energy level type of orbital which contains the electron in the highest energy level [3] , is made. shape of molecule bond angle

Q1(e)

Short Answer 1 mark

Gallium oxide, Ga NaOH(aq).

Q1(i)

Short Answer 1 mark

Suggest the equation for the reaction between Ga

Q1(ii)

Short Answer 1 mark

Suggest an equation for the reaction between gallium oxide and NaOH(aq). [Total: 12]

Short Answer 1 mark

Nitric acid can be made in a 3-stage process. Stage 1 Ammonia is oxidised by oxygen from the air, to form nitrogen monoxide and water. This platinum catalyst. Stage 2 Nitrogen monoxide reacts with more oxygen to form nitrogen dioxide. 2NO + O 2NO Stage 3 Nitrogen dioxide reacts with water to make nitric acid and nitrogen monoxide.3NO + H + NO

Q2(a)

Short Answer 1 mark

Write an equation to show the reaction occurring in stage 1.

Q2(b)

Short Answer 1 mark

Draw a 'dot-and-cross' diagram to show the arrangement of outer electrons in a molecule of ammonia.

Q2(c)

Short Answer 2 marks

(i) In the boxes, give the oxidation numbers of nitrogen in the nitrogen-containing species for the reaction in stage 3.3NO + H + NO

Q2(ii)

Short Answer 1 mark

Explain why the reaction in stage 3 is described as a disproportionation reaction. Include reference to transfer of electrons in your answer.

Q2(d)

Short Answer 1 mark

The release of nitrogen monoxide into the atmosphere causes atmospheric pollution. State and explain the effect of nitrogen monoxide gas in contact with moist air.

Q2(e)

Short Answer 3 marks

The nitric acid made in stage 3 can then be reacted with ammonia to form ammonium nitrate. Stage 3 3NO + H + NO + HNO Calculate the volume of nitrogen dioxide, measured at room temperature and pressure, required to make 40 tonnes of ammonium nitrate. Show your working. volume of nitrogen dioxide =

Q2(f)

Short Answer 1 mark

State one use of ammonium nitrate. [Total: 12] 3 Sucrose, C , reacts with water to form glucose and fructose in reaction A. + H glucose fructose reaction AOHH COHHOHHOHH COHHOHO

Q2(a)

Short Answer 1 mark

Suggest a name for this type of reaction.

Q2(b)

Short Answer 1 mark

Explain in detail, why glucose and fructose are a pair of structural isomers. Your answer should refer specifically to these two molecules.

Q2(c)

Short Answer 1 mark

Reaction A occurs faster in the presence of an enzyme. This is reaction B. Predict a value for the activation energy of reaction A. Predict a value for the enthalpy change for reaction B.

Q2(iii)

Short Answer 1 mark

Sketch a labelled energy level diagram for reaction B. Use relevant values from (c)(i) and

Q2(c)

Short Answer 1 mark

(ii). energy / kJ mol progress of reaction [2] , is completely combusted. The heat energy produced is used to These data can be used to calculate the enthalpy change of combustion of sucrose.

Q2(i)

Short Answer 1 mark

Explain what is meant by the term enthalpy change of combustion of sucrose . , for the combustion of sucrose. Assume that all of the heat energy produced is transferred to the water. Show your working. [3] [Total: 12]

Q4(a)

MCQ 1 mark

An unlabelled bottle contains a straight-chain halogenoalkane, Q. The molecular formula of Q is C X, where X is a halogen; bromine, chlorine or iodine. A test is carried out to identify the halogen present in Q. A sample of Q is added to NaOH(aq) and warmed. Dilute nitric acid is then added followed by a few drops of aqueous silver nitrate. A cream precipitate is observed.

test is carried out to identify the halogen present in Q.

sample of Q is added to NaOH(aq) and warmed. Dilute nitric acid is then added followed by

Q4(i)

Short Answer 1 mark

Suggest the identity of X.

Q4(ii)

Short Answer 1 mark

Write an ionic equation to describe the formation of the cream precipitate. Include state symbols.

Q4(iii)

Short Answer 2 marks

Describe a further test which would confirm the identity of X. test expected result

Q4(b)

Short Answer 1 mark

The reaction of Q with NaOH(aq) tends to proceed via an S 2 mechanism.

Q4(i)

Short Answer 1 mark

Suggest the structural formula of the straight-chain halogenoalkane Q.

Q4(ii)

Short Answer 1 mark

Explain why the reaction tends to proceed via an S 2 mechanism rather than an S mechanism.

Q4(c)

Short Answer 1 mark

Two different halogenoalkanes, P and R, both with the molecular formula C Cl, are separately dissolved in ethanol and heated under reflux with sodium hydroxide. The major organic product of each of these reactions is methylpropene.

Q4(i)

Short Answer 1 mark

Name the type of reaction occurring.

Q4(ii)

Short Answer 1 mark

Write an equation, using molecular formulae, to represent the reaction occurring.

Q4(iii)

Short Answer 1 mark

Draw the skeletal formula of methylpropene.

Q4(iv)

Short Answer 1 mark

Give the names of P and R. [Total: 12]

Short Answer 1 mark

The reaction sequence shows how ethene, C , can be converted into other organic molecules. reaction 1 reaction 2 reaction 6 reaction 3 reaction 4 heat with dilute acid reaction 5

Q5(a)

Structured 6 marks

Complete the table to give reaction name of mechanism name of reagents and conditions

Q5(b)

Short Answer 1 mark

In reaction 3 the organic molecule reacts with HCN and a KCN catalyst.

Q5(i)

Short Answer 3 marks

Complete the diagram to show the mechanism of the reaction occurring. Include all relevant dipoles, lone pairs and curly arrows in your answer.COH

Q5(ii)

Short Answer 1 mark

Name the functional groups present in the product of reaction 3.

Q5(c)

Short Answer 1 mark

Draw the structure of the organic molecule W formed in reaction 4. [1] [Total: 12] 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.

Paper Details

Board	CAIE
Level	A Level
Subject	Chemistry
Code	`9701`
Year	2020
Session	May/June
Q&A	39 questions

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