Isomerism: optical — Paper 1 · A Level Chemistry 9701

40 Which statements about lactic acid, CH3CH(OH)CO2H, are correct? 1 Lactic acid forms optical isomers. 2 Two hydrogen atoms per lactic acid molecule can be involved in hydrogen bonding. 3 Lactic acid would form an aldehyde when oxidised by acidified potassium dichromate(VI).

1 marks

Answer: B

This question in 9701/11 May/June 2006

19 Which molecules, each with a linear carbon chain, can have an optically active isomer? I II III IV C3H6BrI C3H4BrI C3H6I2 C3H4Br2 A I and II only B I, II and III only C II and III only D I, II and IV only

1 marks

Answer: B

This question in 9701/11 Oct/Nov 2007

40 Monopotassium citrate is used as an emulsifying agent in powdered milk and in powdered soups. It may be represented by the formula shown. CH2CO2H HO C CO2 K+ – CH2CO2H Which statements about monopotassium citrate are correct? 1 It can form optical isomers. 2 It can act as a dibasic acid. 3 It can form esters with both acids and alcohols.

1 marks

Answer: C

This question in 9701/11 Oct/Nov 2007

29 Which compound is both chiral and acidic? A B C D H CO2H CH3 OH CH2Br CH(OH)CO2H C HCO2CH CH2CO2H C CH3 H CO2H

1 marks

Answer: D

This question in 9701/11 May/June 2008

30 Which compound exhibits both cis-trans and optical isomerism? A CH3CH=CHCH2CH3 B CH3CHBrCH=CH2 C CH3CBr=CBrCH3 D CH3CH2CHBrCH=CHBr

1 marks

Answer: D

This question in 9701/11 May/June 2010

28 Which compound exhibits both cis-trans and optical isomerism? A CH3CH=CHCH2CH3 B CH3CHBrCH=CH2 C CH3CBr=CBrCH3 D CH3CH2CHBrCH=CHBr

1 marks

Answer: D

This question in 9701/12 May/June 2010

38 Glyceraldehyde, HOCH2CH(OH)CHO, is formed during photosynthesis, and contains a chiral carbon atom. Which reagents will react with glyceraldehyde to produce an organic product without a chiral carbon atom? 1 warmed acidified K2Cr2O7 2 NaBH4 3 Tollens’ reagent

1 marks

Answer: B

This question in 9701/11 Oct/Nov 2010

40 Glyceraldehyde, HOCH2CH(OH)CHO, is formed during photosynthesis, and contains a chiral carbon atom. Which reagents will react with glyceraldehyde to produce an organic product without a chiral carbon atom? 1 warmed acidified K2Cr2O7 2 NaBH4 3 Tollens’ reagent

1 marks

Answer: B

This question in 9701/13 Oct/Nov 2010

29 This question should be answered by considering the reactions of KMnO4 with different functional groups under the stated conditions. The diagram shows the structure of the naturally-occurring molecule cholesterol. H3C CH3 H CH3 H H H HO cholesterol Cholesterol is separately treated with ● cold, dilute acidified KMnO4, ● hot, concentrated acidified KMnO4. What is the change in the number of chiral carbon atoms in the molecule during each reaction? cold, dilute acidified hot, concentrated acidified KMnO4 KMnO4 A +1 0 B +1 –1 C +2 0 D +2 –1

1 marks

Answer: D

This question in 9701/12 May/June 2011

38 Which compounds when heated under reflux with an excess of hot acidified potassium dichromate(VI), give a product with a chiral centre? CH3 1 CH3CH2CCH2OH H CH3 2 CH3CH2CCH2OH CO2H CH3 3 CH3COCCH(OH)CH3 CO2CH3

1 marks

Answer: D

This question in 9701/12 May/June 2011

28 An unpleasant smelling chemical produced in the human armpit is 3-methylhex-2-enoic acid. CH3 CH3 CH2 CH2 C CH C OH O If this compound is reacted with a cold, dilute, acidified solution of potassium manganate(VII), how many chiral centres will be produced? A 0 B 1 C 2 D 3

1 marks

Answer: C

This question in 9701/11 Oct/Nov 2011

27 The molecule shown is optically active. Cl H Cl H H Cl C C C C C Cl H H H H Cl C H H How many chiral carbon atoms are present in this molecule? A 1 B 2 C 3 D 4

1 marks

This question in 9701/12 Oct/Nov 2011

26 An unpleasant smelling chemical produced in the human armpit is 3-methylhex-2-enoic acid. CH3 CH3 CH2 CH2 C CH C OH O If this compound is reacted with a cold, dilute, acidified solution of potassium manganate(VII), how many chiral centres will be produced? A 0 B 1 C 2 D 3

1 marks

Answer: C

This question in 9701/13 Oct/Nov 2011

22 Menthol is an important compound extracted from the peppermint plant. CH3 OH H3C CH3 menthol How many chiral centres are there in one molecule of menthol? A 1 B 2 C 3 D 4

1 marks

Answer: C

This question in 9701/11 Oct/Nov 2012

22 Menthol is an important compound extracted from the peppermint plant. CH3 OH H3C CH3 menthol How many chiral centres are there in one molecule of menthol? A 1 B 2 C 3 D 4

1 marks

Answer: C

This question in 9701/12 Oct/Nov 2012

28 Which compound is optically active and could also be oxidised to a ketone? A 2-methylbutan-1-ol B 3-methylhexan-3-ol C 3-methylpentan-2-ol D propan-2-ol

1 marks

Answer: C

This question in 9701/13 Oct/Nov 2012

20 The following compounds are found in the seaweed Asparagopsis taxiformis. Which compound could show both cis-trans isomerism and optical isomerism? A B C D Cl Cl O Br Cl H H H Br Br Br C Br C C C Br C Br C C Br C C Cl C C I C C Br H I H Cl H Br H

1 marks

Answer: B

This question in 9701/11 May/June 2013

25 Pentane, C5H12, is reacted with chlorine in the presence of ultraviolet light. A compound R is found in the products. R has molecular formula C5H10Cl 2. Each molecule of R contains one chiral carbon atom. Which two atoms of the pentane chain could be bonded to chlorine atoms in this isomer? A 1 and 3 B 1 and 5 C 2 and 3 D 2 and 4

1 marks

Answer: A

This question in 9701/11 May/June 2013

40 The compounds below are treated with hydrogen cyanide. Which compounds react and produce a molecule containing a chiral centre? 1 butanal 2 pentan-3-one 3 2-chlorobutane

1 marks

Answer: D

This question in 9701/12 Oct/Nov 2013

30 Artemisinin is a powerful anti-malarial drug. CH3 O O CH3 O O O CH3 artemisinin How many chiral centres are there in each molecule of artemisinin? A 4 B 6 C 7 D 8

1 marks

Answer: C

This question in 9701/12 May/June 2014

26 Corticosterone is a hormone involved in the metabolism of carbohydrates and proteins. O OH CH3 HO CH3 O corticosterone How many chiral centres are there in one molecule of corticosterone? A 5 B 6 C 7 D 8

1 marks

Answer: C

This question in 9701/11 Oct/Nov 2014

37 Propanal will react with hydrogen cyanide to form 2-hydroxybutanenitrile. A suitable catalyst for this reaction is sodium cyanide. NaCN CH3CH2CHO + HCN CH3CH2CH(OH)CN Which statements about the reaction of propanal with hydrogen cyanide are correct? 1 The CN– ion attacks the propanal molecule to form an intermediate ion. 2 The product of the reaction has a chiral carbon atom. 3 The CN– ion is a stronger electrophile than the HCN molecule.

1 marks

Answer: B

This question in 9701/11 Oct/Nov 2014

26 Corticosterone is a hormone involved in the metabolism of carbohydrates and proteins. O OH CH3 HO CH3 O corticosterone How many chiral centres are there in one molecule of corticosterone? A 5 B 6 C 7 D 8

1 marks

Answer: C

This question in 9701/12 Oct/Nov 2014

37 Propanal will react with hydrogen cyanide to form 2-hydroxybutanenitrile. A suitable catalyst for this reaction is sodium cyanide. NaCN CH3CH2CHO + HCN CH3CH2CH(OH)CN Which statements about the reaction of propanal with hydrogen cyanide are correct? 1 The CN– ion attacks the propanal molecule to form an intermediate ion. 2 The product of the reaction has a chiral carbon atom. 3 The CN– ion is a stronger electrophile than the HCN molecule.

1 marks

Answer: B

This question in 9701/12 Oct/Nov 2014

30 Geranyl ethanoate is present in ginger and cocoa, and is used in shampoos and soaps as a perfume. It reacts with an excess of bromine in an organic solvent to give X, a bromo-derivative. O Br2 O bromo-derivative geranyl ethanoate X Including geranyl ethanoate, how many cis-trans isomers are there of geranyl ethanoate, and how many chiral centres are there in X? chiral centres cis-trans isomers in X A 2 3 B 2 4 C 4 3 D 4 4

1 marks

Answer: A

This question in 9701/11 May/June 2016

37 The diagram shows a compound used as a flame retardant. Br Br Br Br Br Br Which statements about this structure are correct? 1 The empirical formula is C2H3Br. 2 The C12 ring is not planar. 3 There are six chiral carbon atoms.

1 marks

Answer: A

This question in 9701/12 May/June 2016

38 One of the active ingredients in tea-tree oil is terpinen-4-ol. In the diagram of the skeletal formula of terpinen-4-ol, three of the carbon atoms are labelled 1, 2 and 3. Which of the labelled carbon atoms are chiral? 2 1 HO 3 terpinen-4-ol

1 marks

Answer: D

This question in 9701/12 May/June 2016

21 The diagram shows the structure of vitamin A. CH3 CH3 H3C CH3 OH CH3 vitamin A How many chiral centres are present in one vitamin A molecule? A 0 B 1 C 2 D 3

1 marks

Answer: A

This question in 9701/11 Oct/Nov 2016

21 The diagram shows the structure of vitamin A. CH3 CH3 H3C CH3 OH CH3 vitamin A How many chiral centres are present in one vitamin A molecule? A 0 B 1 C 2 D 3

1 marks

Answer: A

This question in 9701/13 Oct/Nov 2016

29 Which compound is chiral and reacts with Na2CO3 to give CO2? A B C D CH3 OH CH2Br CH(Br)CO2H H CO2H C HCO2CH CH2 C CH3 H CO2H CH3

1 marks

Answer: D

This question in 9701/12 May/June 2017

37 Which compounds contain a chiral centre? 1 2-hydroxybutanoic acid 2 3-hydroxybutanoic acid 3 4-hydroxybutanoic acid

1 marks

Answer: B

This question in 9701/12 May/June 2017

21 Structural isomerism and stereoisomerism should be considered when answering this question. If a molecule contains two non-identical chiral carbon atoms, four optical isomers exist. How many isomers are there with ● molecular formula C7H14O and ● a five-membered ring and ● a tertiary alcohol group? A 4 B 5 C 9 D 13

1 marks

Answer: C

This question in 9701/13 May/June 2017

40 Propanal will react with hydrogen cyanide to form 2-hydroxybutanenitrile. A suitable catalyst for this reaction is sodium cyanide. NaCN CH3CH2CHO + HCN CH3CH2CH(OH)CN Which statements about this reaction of propanal with hydrogen cyanide are correct? 1 The CN– ion attacks the propanal molecule to form an intermediate ion. 2 The product of the reaction has a chiral carbon atom. 3 The CN– ion is a stronger electrophile than the HCN molecule.

1 marks

Answer: B

This question in 9701/13 May/June 2017

29 Compound G ● has a chiral centre, ● gives a positive result with alkaline aqueous iodine, ● does not give a silver mirror with Tollens’ reagent. What could compound G be? A 1-hydroxybutan-2-one B 2-hydroxybutanal C 3-hydroxybutanal D 3-hydroxybutan-2-one

1 marks

Answer: D

This question in 9701/12 Oct/Nov 2017

39 Propanal reacts with hydrogen cyanide to form 2-hydroxybutanenitrile. A suitable catalyst for this reaction is sodium cyanide. NaCN CH3CH2CHO + HCN CH3CH2CH(OH)CN Which statements about the reaction of propanal with hydrogen cyanide are correct? 1 HCN is a weaker nucleophile than the nucleophile provided by NaCN. 2 The reaction mechanism involves two steps. 3 The product of the reaction has a chiral carbon atom.

1 marks

Answer: A

This question in 9701/12 Feb/March 2018

20 Fructose is a sugar with more than one chiral centre. The fructose molecule is shown with X, Y and Z indicating three carbon atoms. OH H C H X C O HO C H H C OH Y H C OH H C H Z OH fructose Which carbon atoms are chiral centres? A X, Y and Z B X and Y only C X only D Y only

1 marks

Answer: B

This question in 9701/11 May/June 2018

25 Compound Q ● contains a chiral centre, ● gives a positive result with Fehling’s reagent, ● gives a positive result with alkaline aqueous iodine. What could compound Q be? A 1-hydroxybutanone B 2-hydroxybutanal C 3-hydroxybutanal D 3-hydroxybutanone

1 marks

Answer: C

This question in 9701/11 May/June 2018

27 Which compound shows optical isomerism and gives a positive test with alkaline aqueous iodine? A CH3COCH(OH)CH3 B CH3COCH2CH2OH C HOCH2CH(CH3)CHO D (CH3)2C(OH)CHO

1 marks

Answer: A

This question in 9701/11 Oct/Nov 2018

37 Which bromopropenes would react with cold bromine in the dark to form a product containing a chiral carbon atom? 1 CHBr=CHCH3 2 CH2=CHCH2Br 3 CH2=CBrCH3

1 marks

Answer: D

This question in 9701/12 Oct/Nov 2018

39 Which statements about 2-methylbutan-1-ol are correct? 1 It can give HCl (g) on reaction with PCl 5. 2 It can be oxidised to give an aldehyde. 3 It displays optical isomerism.

1 marks

Answer: A

This question in 9701/12 Oct/Nov 2018

39 The compounds listed are reacted with hydrogen cyanide. Which compounds produce a molecule containing a chiral centre? 1 butanal 2 butanone 3 pentan-2-one

1 marks

Answer: A

This question in 9701/12 Feb/March 2019

30 Which compound is chiral? A 1-chloro-3-methylbutane B 2-chloro-2-methylbutane C 2-chloro-3-methylbutane D 3-chloropentane Section B

1 marks

Answer: C

This question in 9701/11 May/June 2019

37 The diagram shows a compound used as a flame retardant. Br Br Br Br Br Br Which statements about this structure are correct? 1 The empirical formula is C2H3Br. 2 The C12 ring is not planar. 3 There are six chiral carbon atoms.

1 marks

Answer: A

This question in 9701/12 May/June 2019

37 Which compounds have optical isomers? 1 2 3 H O CH3 C H C OH O O H C OH OH HO C CH CH C OH H C OH CH CH3 CH3 H C OH H

1 marks

Answer: B

This question in 9701/13 May/June 2019

28 The structure of compound Q is shown. compound Q O O O O How many chiral centres are present in a molecule of Q? A 4 B 5 C 6 D 7

1 marks

Answer: D

This question in 9701/11 May/June 2020

30 The diagram shows the structure of buta-1,3-diene. buta-1,3-diene H H C C H H C C H H The addition reaction between buta-1,3-diene and two molecules of hydrogen bromide can produce three structurally isomeric products. How many of these products have at least one chiral centre? A 0 B 1 C 2 D 3

1 marks

Answer: C

This question in 9701/12 May/June 2020

30 Compound X has the structure shown. compound X O Which type of carbonyl group is present and how many chiral centres are there in one molecule of X? carbonyl chiral group centres A aldehyde 0 B aldehyde 1 C ketone 0 D ketone 1

1 marks

Answer: D

This question in 9701/13 May/June 2020

29 Which compound is chiral and reacts with Na2CO3 to give CO2? A B C D CH3 OH CH2Br CH(Br)CO2H H CO2H C HCO2CH CH2 C CH3 H CO2H CH3

1 marks

Answer: D

This question in 9701/11 Oct/Nov 2020

29 Which compound is chiral and reacts with Na2CO3 to give CO2? A B C D CH3 OH CH2Br CH(Br)CO2H H CO2H C HCO2CH CH2 C CH3 H CO2H CH3

1 marks

Answer: D

This question in 9701/13 Oct/Nov 2020

22 Which compound could show both cis-trans isomerism and optical isomerism? A B C D Cl Cl O Br Cl H H H Br Br Br C Br C C C Br C C C Br C C Br C C Cl C C I Br H I H Cl H Br H

1 marks

Answer: B

This question in 9701/11 May/June 2021

20 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

1 marks

Answer: B

This question in 9701/12 May/June 2021

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.

1 marks

Answer: D

This question in 9701/13 May/June 2021

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

1 marks

Answer: A

This question in 9701/12 Oct/Nov 2021

39 Which of the reactions give products containing a chiral centre? 1 CH2(OH)COCO2H + an excess of HCN 2 CH2(OH)COCO2H + an excess of NaBH4 3 CH2(OH)COCO2H + an excess of LiAl H4

1 marks

Answer: B

This question in 9701/12 Oct/Nov 2021

27 Which compound will react with LiAl H4 to form two optical isomers? A CH3CH2COCH3 B CH3CH2CH2CHO C CH3CH2COCH2CH3 D CH3CH(CH3)CH2CO2H

1 marks

Answer: A

This question in 9701/11 May/June 2022

26 A skeletal formula is shown. What is the total number of stereoisomers including the one shown? A 4 B 6 C 8 D 16

1 marks

Answer: C

This question in 9701/12 May/June 2022

28 The diagram shows the structural formula of mevalonic acid. mevalonic acid H OH H H HO2C C C C C OH H CH3 H H Which reagent and conditions will react with mevalonic acid to produce an organic compound without a chiral carbon atom? A heat under reflux with CH3OH / H+ B heat under reflux with Cr2O7 2– / H+ C Na at room temperature D PCl 5 at room temperature

1 marks

Answer: B

This question in 9701/13 May/June 2022

40 One molecule of an addition polymer containing 2000 repeat units has an Mr of 112 000. The polymer molecule contains chiral centres. What is a possible monomer for this polymer? A CH2=CHCH3 B CH2=C(CH3)2 C CH2=CHCH2CH3 D CH2=CHCH2CH2CH3

1 marks

Answer: C

This question in 9701/13 May/June 2022

27 How many chiral carbon atoms are there in one molecule of 2,2,4,5-tetramethylhexan-3-ol? A 1 B 2 C 3 D 4

1 marks

Answer: B

This question in 9701/11 Oct/Nov 2022

27 How many chiral carbon atoms are there in one molecule of 2,2,4,5-tetramethylhexan-3-ol? A 1 B 2 C 3 D 4

1 marks

Answer: B

This question in 9701/13 Oct/Nov 2022

26 The compound aspartame is widely used as a sweetener in ‘diet’ soft drinks. aspartame CH3 O O O HO C6H5 NH O NH2 Aspartame is chiral. (There are no chiral carbon atoms in C6H5.) How many chiral carbon atoms are present in a molecule of aspartame? A 1 B 2 C 3 D 4

1 marks

Answer: B

This question in 9701/11 Oct/Nov 2023

26 The drug cortisone has the formula shown. cortisone OH OH O O O In addition to those chiral centres marked by an asterisk (*), how many other chiral centres are present in the cortisone molecule? A 0 B 1 C 2 D 3

1 marks

Answer: D

This question in 9701/12 Feb/March 2024

32 Compound X is a single, pure, optical isomer. Compound X is heated with an excess of concentrated H2SO4. Only one organic product is formed. What is compound X? A B C D OH OH CH2OH HO

1 marks

Answer: D

This question in 9701/11 May/June 2024

36 Which compound, on reaction with hydrogen cyanide, produces a compound with a chiral centre? A CH3CHO B CH3CH2COCH2CH3 C CH3CO2CH3 D HCHO

1 marks

Answer: A

This question in 9701/11 Oct/Nov 2024

26 Compound X is found in cell walls of some bacteria. Its structural formula is shown. compound X CH3(CH2)17CH=CH(CH2)17CH(OH)CH(CH3)CO2H How many stereoisomers are there with this structural formula? A 2 B 4 C 6 D 8

1 marks

Answer: D

This question in 9701/12 Oct/Nov 2024

36 The diagram shows the structure of progesterone. progesterone O O Which statement about progesterone is correct? A One molecule contains four chiral carbon atoms only; the molecular formula is C19H26O2. B One molecule contains four chiral carbon atoms only; the molecular formula is C21H30O2. C One molecule contains six chiral carbon atoms; the molecular formula is C19H26O2. D One molecule contains six chiral carbon atoms; the molecular formula is C21H30O2.

1 marks

Answer: D

This question in 9701/12 Feb/March 2025

38 The structure of the testosterone molecule is shown. O CH3 OH CH3 C2 C1 Which statements are correct? 1 Carbon atoms C1 and C2 can be oxidised with acidified K2Cr2O7. 2 There are fewer than 27 hydrogen atoms in one testosterone molecule. 3 There are six chiral carbon atoms in one testosterone molecule. A 1 only B 2 and 3 C 2 only D 3 only

1 marks

Answer: D

This question in 9701/11 May/June 2025

38 Fructose is a sugar with more than one chiral centre. The fructose molecule is shown with X, Y and Z indicating three carbon atoms. C C C C C C OH OH H H HO H H OH H OH H H O X Y Z fructose Which carbon atoms are chiral centres? A X, Y and Z B X and Y only C X only D Y only

1 marks

Answer: B

This question in 9701/13 May/June 2025

31 Testosterone is an optically active organic molecule. testosterone OH O How many chiral centres are there in one molecule of testosterone? A 5 B 6 C 7 D 8

1 marks

Answer: B

This question in 9701/14 May/June 2025

25 The diagrams show skeletal formulas of some isomers of C6H12O. O 1 2 O O 3 4 O Which statement is correct? A 1 and 3 are chain isomers of each other and positional isomers of each other. B 2 and 3 are functional group isomers of each other and both have a chiral centre. C 1 and 4 are functional group isomers of each other and both have a chiral centre. D 2 and 4 are positional isomers of each other and functional group isomers of each other.

1 marks

Answer: B

This question in 9701/11 Oct/Nov 2025

26 The skeletal formulas of two compounds are shown. progesterone O O testosterone OH O Which statements about progesterone and testosterone are correct? A They both contain a ketone group, and they both have geometrical isomers due to the C=C bond. B They have the same molecular formula, and they both have geometrical isomers. C They have the same number of chiral carbons, and they have the same molecular formula. D They have the same number of chiral carbons, and they both contain a ketone group.

1 marks

Answer: D

This question in 9701/11 Oct/Nov 2025

25 The diagrams show skeletal formulas of some isomers of C6H12O. O 1 2 O O 3 4 O Which statement is correct? A 1 and 3 are chain isomers of each other and positional isomers of each other. B 2 and 3 are functional group isomers of each other and both have a chiral centre. C 1 and 4 are functional group isomers of each other and both have a chiral centre. D 2 and 4 are positional isomers of each other and functional group isomers of each other.

1 marks

Answer: B

This question in 9701/13 Oct/Nov 2025

26 The skeletal formulas of two compounds are shown. progesterone O O testosterone OH O Which statements about progesterone and testosterone are correct? A They both contain a ketone group, and they both have geometrical isomers due to the C=C bond. B They have the same molecular formula, and they both have geometrical isomers. C They have the same number of chiral carbons, and they have the same molecular formula. D They have the same number of chiral carbons, and they both contain a ketone group.

1 marks

Answer: D

This question in 9701/13 Oct/Nov 2025