AQA A Level Chemistry

Topic Questions

7.1 Optical Isomerism (A-level only)

11 mark

Which statement is the most correct for an optical isomer?

  • Optical isomers are molecules that have the same structural formula but have the atoms arranged differently in space

  • Four different atoms or groups of atoms around a carbon atom causes optical isomerism

  • Optical isomerism occurs as a result of restricted rotation about a carbon–carbon double bond

  • Optical isomers are superimposable mirror images of each other called enantiomers

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21 mark

Which carbon atom is the chiral centre in the following molecule?

7-1-e-q2-aqa-al-chemistry-mcq

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31 mark

Which compound contains a chiral carbon?

  • Propanal

  • Butanone

  • Butan-2-ol

  • Cyclopentanol

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41 mark

Which compound does not contain a chiral carbon?

7-1-e-q4-aqa-al-chemistry-mcq

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51 mark

Which of the following can form a racemic mixture?

  • The product of but-1-ene and chlorine

  • The major product of propene and hydrogen chloride

  • The minor product of but-1-ene and hydrogen bromide

  • The product of ethene and bromine

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11 mark

Which of the following reaction mixtures forms a racemate when the chemicals react?

  • 2-hydroxy-2-methylpropanal with acidified potassium dichromate(VI) solution

  • Ethanol with methanoic acid

  • But-1-ene with bromine water

  • 2-hydroxy-2-methylpropanal with sodium tetrahydridoborate(III) solution

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21 mark

Which compound forms a reduction product capable of exhibiting optical isomerism?

  • CH3CH2COCH2CH3

  • CH3CH2CH2COCH3

  • CH(CH3)2CH2CHO

  • C(CH3)3CHO

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31 mark

Arthrinin-F is a relatively novel compound isolated from fungus.

7-1-h-q3-aqa-al-chemistry-mcq

How many chiral centres does Arthrinin-F have in its structure?

  • 4

  • 6

  • 11

  • 14

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41 mark

Which one of the following statements about but-3-en-2-ol, CH2CHCHOHCH3, is not true?

  • It has optical isomers

  • It has stereoisomers

  • It will turn an acidified potassium dichromate(VI) solution green

  • It shows a strong absorption in the infra-red at about 1650 cm−1

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51 mark

N,N-Dimethyl-2-hydroxy-3-methylbutanamide can exist as a pair of optical isomers.

Which is the correct structure for an N,N-dimethyl-2-hydroxy-3-methylbutanamide enantiomer?

qNttoDeM_7-1-h-q5-aqa-al-chemistry-mcq

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11 mark

Which statement is true about optical isomerism?

  • Optical isomers have a different arrangement of carbon atoms in the skeleton of the molecule

  • Optical isomers have a different boiling point

  • Optical isomers have the same structural formula

  • Optical isomers have four different atoms attached to the chiral carbon

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21 mark

The molecule shown below is called 2,3-dihydroxybutanedioic acid

7-1-m-q2-aqa-al-chemistry-mcq

What can be deduced from the structure?

  • There are four asymmetric carbon atoms

  • The structure shown rotates plane polarised light to the right

  • 2,3-dihydroxybutanedioic acid is a racemate

  • The molecule has two chiral centres

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31 mark

Ethanal reacts with hydrogen cyanide followed by hydrochloric acid to make 2-hydroxypropanoic acid in a two-step reaction sequence:

7-1-m-q3-aqa-al-chemistry-mcq

Which row is true?

 

             Reactant     

    Product of step 1  

  Product of step 2

  A   

optically active

optically active

optically active

B

  optically inactive

racemate

racemate

C

optically active

optically inactive

optically active

D

optically active

racemate

racemate

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41 mark

Which of the following compounds will produce optical isomers when it undergoes reduction?

  • CH3COCH3

  • CH3CH=CH2

  • CH3CH2COCH3

  • CH3CH2COOH

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51 mark

Which of the following reactions produces a racemate?

  • CH3CH2COCH3  + HCN

  • CH3CH2CBrCH2  + Br2

  • CH3CH2CHBrCH3  + NaOH

  • CH3CH2CH2CH2OH + H2SO4

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