IBChemistryHLTopic QuestionsClassification of MatterFunctional Groups: Classification of Organic Compounds

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First teaching 2023

First exams 2025

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Functional Groups: Classification of Organic Compounds (HL IB Chemistry)

Topic Questions

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11 mark

Which of the following shows the correct order of boiling points for pentane, butane and propane?

  • CH3CH2CH3 > CH3CH2CH2CH3 > CH3CH2CH2CH2CH3

  • CH3CH2CH2CH2CH3 > CH3CH2CH2CH3 > CH3CH2CH3

  • CH3CH2CH2CH3 > CH3CH2CH2CH2CH3 > CH3CH2CH3 

  • CH3CH2CH3 > CH3CH2CH2CH2CH3 > CH3CH2CH2CH3  

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21 mark

Which of the following statements about propanal, CH3CH2CHO, and propanone, CH3COCH3 is not correct? 

The compounds have:

  • molecular ion peaks at different mass to charge ratios

  • different fragmentation patterns in the mass spectrum

  • absorption in the infrared spectrum due to the carbonyl group

  • a different fingerprint region in the infrared spectrum

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31 mark

Nitrogen trichloride has the formula NCl3. A sample was found to contain only 14N, and chlorine atoms with mass numbers 35 and 37. 

Which of the following is an incorrect ion and mass/charge ratio responsible for the molecular ion peaks found in the mass spectrum of nitrogen trichloride? 

 

ion

m/e

A

N(35Cl)3+

119

B

N(35Cl)237Cl+

121

C

N35Cl(37Cl)2+

123

D

N(37Cl)2+

125

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41 mark

Which of the following cannot be obtained from an infrared spectrum?

  • the molecular mass

  • the presence of C=O bonds

  • the presence of O-H bonds

  • the identity of a compound through comparison with other spectra

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51 mark

What information can be determined from the infrared spectrum of a molecule?

  • The number of hydrogens

  • The number of hydrogen environments

  • The type of bonds present

  • The relative molecular mass

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61 mark

Which of the following bonds will produce strong absorptions in the infrared part of the electromagnetic spectrum? 

    1.    C-N
    2.    O=O
    3.    C=O

  • I and II only  

  • I and III only  

  • II and III only 

  • I, II and III

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71 mark

Which of the following is true about the fingerprint region in the IR spectrum of alcohols?

  • The fingerprint region is where single bonds can be identified in the IR spectrum  

  • The fingerprint region is unique to every molecule  

  • The fingerprint region does not provide useful information about molecules 

  • A functional group can be identified from the fingerprint region

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81 mark

Which of the following statements is correct about spectroscopic techniques for organic molecules?

  • Information about bond vibrations can be deduced from mass spectroscopy 

  • The values of carbon–hydrogen bond lengths can be found from 1H NMR spectroscopy 

  • The number of hydrogen atoms can be determined from infrared spectroscopy

  • Information about molecular structure can be found from mass spectroscopy

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91 mark

In the 1H NMR spectrum of 3-methylbutan-1-ol what is the ratio of the peak areas under each signal?

  • 6 : 1 : 2 : 2 : 1

  • 3 : 3 : 1 : 5 : 1

  • 6 : 1 : 5 : 1

  • 3 : 3 : 1 : 2 : 3

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101 mark

Which of the following types of spectroscopic identification will involve bond fission in organic molecules?

  • Nuclear magnetic spectroscopy  

  • Infrared spectroscopy 

  • Mass spectrometry 

  • X-ray crystallography

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111 mark

Which pairs of homologous series do not have the same C:H ratio in their general formulae?

  • aldehydes and ketones

  • alkanes and alkenes

  • carboxylic acids and esters

  • alkenes and aldehydes

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121 mark

Which of the following molecules are hydrocarbons?

10-1-q2-ib-chemisrey-mcq

  • All

  • 1 and 2

  • 1, 2 and 3

  • 2, 3 and 4

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131 mark

What is the correct formula for 1-fluoro-3-methylbut-2-ene?

          A           

                     Molecular                          

         CH2FCH2C(CH3)CH3

B

Empirical

C5H9F

C

Displayed

 10-1-q3-ib-chemisrey-mcq

D

Skeletal

 

10-1-e-q3-ib-chemistry-mcq    

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141 mark

Considering only structural isomers, what is the number of alcohols of each type with the formula C5H12O?

             

         primary        

       secondary      

      tertiary    

A

B

C

D

3

4

4

5

3

2

3

2

2

2

1

1

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151 mark

Which of the following is the displayed formula for ethylamine?

10-1-q5-ib-chemisrey-mcq

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161 mark

Identify which of the hydrocarbons shown below does not belong in the same homologous series as the other compounds

  • C5H12

  • C6H12

  • C7H16

  • C8H18

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171 mark

Identify the functional group that is ringed in the molecule shown below:

10-1-q7-ib-chemisrey-mcq

  • hydroxyl

  • carboxyl

  • ether

  • carbonyl

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181 mark

What is the IUPAC name of the following molecule?10-1-q8-ib-chemisrey-mcq

  •  2-chloro-3-ethylbutane

  • 3-methyl-4-chloropentane

  • 2-ethyl-3-chlorobutane

  • 2-chloro-3-methylpentane

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191 mark

What is the IUPAC name of the following molecule?10-1-q9-ib-chemisrey-mcq

  • 3,3-dimethylpropanoic acid

  • 1,1-dimethylpropanoic acid

  • 3-methylbutanoic acid

  • 2-methylbutanoic acid

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201 mark

Which of the halogenoalkanes shown contains a secondary carbon atom?

  • (CH3)2CHCH2Cl

  • CH3(CH2)3CH2Cl

  • (CH3)3CCl

  • CH3CHClCH2CH3

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21
Sme Calculator1 mark

Which molecule contains a chiral carbon?

  • 1-chloro-2-methylbutane

  • 2-methylpropane

  • Butane

  • 2-chloropropane

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22
Sme Calculator1 mark

What is name of this compound applying IUPAC rules?

1f99b13b-fc61-4666-855a-a545bf627b9a

  • Trans-pent-2-ene

  • Trans-but-2-ene

  • But-1-ene

  • Cis-but-2-ene

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23
Sme Calculator1 mark

Which statement about isomerism is correct?

  • A racemic mixture is optically active 

  • Pent-1-ene exhibits stereoisomerism 

  • 1-bromopropane has two optical isomers 

  • 2-amino-3-methylpentane is a diastereomer

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24
Sme Calculator1 mark

Which pair are cis and trans isomers?

  • aIKHR5cw_20-3-a-ib-mcq

  • 20-3-b---ib-mcq

  • 20-3-c---ib-mcq

  • 20-3-d---ib-mcq

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11 mark

The mass spectra of three compounds A, B and C are shown below.

11-1-mcq-q1-fig-1-hard-ib-chemistry

11-1-mcq-q1-fig-2-hard-ib-chemistry

11-1-mcq-q1-fig-3-hard-ib-chemistry

What evidence from the spectra of the three compounds A, B and C, suggests they could be isomers?

  • all show a molecular ion peak at 74

  • all show a molecular ion peak at 13

  • all show a molecular ion peak at 73

  • all show a molecular ion peak at 33

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21 mark

The infrared spectrum below shows an unknown compound.

11-1-mcq-q2-hard-ib-chemistry

bond

wavenumber range/ cm-1

C−O; hydroxyl, ester

1040 – 1300

C═C; aromatic compound, alkene

1500 - 1680

C═O amide

carbonyl, carboxyl

ester

1640 – 1690

1670 – 1740

1710 - 1750

C≡N; nitrile

2200 – 2250

C−H; alkane

2850 – 2950

N−H; amine, amide

3300 – 3500

O−H; carboxyl

hydroxyl

2500 – 3000

3200 - 3600

Which compound could have produced the infrared spectrum?

11-1-mcq-q2-ma-hard-ib-chemistry

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31 mark

The diagram shows an infrared spectrum of a compound.

11-1-mcq-q3-hard-ib-chemistry

bond

wavenumber range/ cm-1

C−O; hydroxyl, ester

1040 – 1300

C═C; aromatic compound, alkene

1500 - 1680

C═O amide

carbonyl, carboxyl

ester

1640 – 1690

1670 – 1740

1710 - 1750

C≡N; nitrile

2200 – 2250

C−H; alkane

2850 – 2950

N−H; amine, amide

3300 – 3500

O−H; carboxyl

hydroxyl

2500 – 3000

3200 - 3600

Which compound would give this spectrum?

  • butanoic acid

  • butanal

  • butan-1-ol

  • 1-bromobutane

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41 mark

Which of the following infrared spectra could show a carboxylic acid?

11-1-mcq-q4-fig-1-hard-ib-chemistry

11-1-mcq-q4-fig-2-hard-ib-chemistry

11-1-mcq-q4-fig-3-hard-ib-chemistry

11-1-mcq-q4-fig-4-hard-ib-chemistry

Bond

Wavenumber range/ cm-1

C−O; hydroxyl, ester

1040 – 1300

C═C; aromatic compound, alkene

1500 - 1680

C═O amide

carbonyl, carboxyl

ester

1640 – 1690

1670 – 1740

1710 - 1750

C≡N; nitrile

2200 – 2250

C−H; alkane

2850 – 2950

N−H; amine, amide

3300 – 3500

O−H; carboxyl

hydroxyl

2500 – 3000

3200 - 3600

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51 mark

A compound XFn is a fluoride of another halogen, X, and it is known that n > 1. The highest m/e peak in the mass spectrum of XFn is assigned to the parent ion and comes as a single peak at m/e = 222. 

Which of the following statements is incorrect?

  • n = 5

  • the compound could contain bromine

  • there are no isotopes of X or F

  • the compound is a fluoride of iodine

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61 mark

An organic compound is analysed by mass spectrometry and infrared spectroscopy. The following data is obtained.

 

mass spectrometry

infrared spectroscopy

molecular ion peak at m/e = 128

sharp peak at 1720 cm-1

fragment ion peak at m/e = 15

no broad peak around 3200 cm-1

 

Bond

Wavenumber range/ cm-1

C−O; hydroxyl, ester

1040 – 1300

C═C; aromatic compound, alkene

1500 - 1680

C═O amide

carbonyl, carboxyl

ester

1640 – 1690

1670 – 1740

1710 - 1750

C≡N; nitrile

2200 – 2250

C−H; alkane

2850 – 2950

N−H; amine, amide

3300 – 3500

O−H; carboxyl

hydroxyl

2500 – 3000

3200 - 3600

 

Which of the following compounds could be consistent with the data given?

11-1-mcq-q6-hard-ib-chemistry

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71 mark

What does the 1H NMR spectrum below tell you about a molecule?

11-1-mcq-q7-hard-ib-chemistry

  • There is only one isotope of hydrogen present in the molecule

  • The molecule is a hydrocarbon

  • There is only one hydrogen atom in the molecule

  • There is only one hydrogen environment in the molecule

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81 mark

How many peaks would you expect to see in a 1H NMR spectrum of methylbenzene?

11-1-mcq-q8-hard-ib-chemistry

  • 3

  • 4

  • 5

  • 6

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91 mark

How many isomers, including structural and stereoisomers, with the formula C5H10 have structures that involve π bonding?

  • 3

  • 4

  • 5

  • 6

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101 mark

Study the formulae shown below and determine which molecules are isomers of each other

I.
CH3(CH2)3CH2CH3
II.
(CH3)2CHCH2CH3
III.
CH3CH(CH3)CH2CH2CH3

  • I and II only

  • I and III only

  • II and III only

  • I, II and III

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111 mark

What is the correct condensed structural formula for 2,2-dibromo-4-methylhexane?

  • CH3CBr2CH(CH3)CH2CH2CH3

  • CH3CHBrCBr(CH3)CH2CH2CH3

  • CH3CBr2CH2CH(CH3)CH2CH3

  • CH3CHBrCH(CH3)CHBrCH2CH3

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121 mark

What is the correct IUPAC name for the molecule shown?

10-1-h-q4-mcqs-ib-chemistry

  • ethoxyethane

  • methoxyethane

  • propanone

  • propanal

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131 mark

Which of the molecules shown below is not an isomer of pentan-2-ol?

  • pentan-1-ol

  • 2-methylbutan-2-ol

  • 2-methylpentan-2-ol

  • pentan-3-ol

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141 mark

Which of the following pairs are functional group isomers?

I.
CH3CH(OH)CH2CH2CH3 and CH3CH2CH(OH)CH2CH3
II.
CH3CH2CH2COOH and HCOOCH2CH2CH3
III.
CH3CH2CH2OH and CH3OCH2CH3

  • I and II only

  • I and III only

  • II and III only

  • I, II and III

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151 mark

What is the correct name of the following molecule using IUPAC rules?

10-1-h-q8-mcqs-ib-chemistry

  • propyl methanoate

  • methyl propanoate

  • methoxypropane

  • butoxymethanal

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161 mark

What types of isomerism can the following molecule show?

10-1-h-q9-mcqs-ib-chemistry

I.
Branch-chain
II.
Positional 
III.
Functional group

  • I and II only

  • I and III only

  • II and III only

  • I, II and III

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17
Sme Calculator1 mark

How many five ringed membered isomers are there of dimethyl cyclopentane? 

  • 3

  • 4

  • 5

  • 6

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18
Sme Calculator1 mark

Which structure is the correct cis trans isomer of trans-1,2-dibromocyclobutane? 

  • 071e94cd-60a9-4a2d-ae93-5b18d9c18acb

     

  • IB 20.3 MCQ H Option B

     

  • IB 20.3 MCQ H Option C

     

  • 69b446c6-efd4-42a0-b85c-f2145b750414

     

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19
Sme Calculator1 mark

Which molecule has a chiral centre? 

  • CH3OCH2CH3

  • CH3CH2CHO

  • CH3CH(NH2)CH3

  • CH3CH(OH)CH2CH3

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20
Sme Calculator1 mark

Arthrinin-F is a compound isolated from fungus.

1-1

What is the correct number of chiral carbons in the structure?

  • 2

  • 3

  • 4

  • 5

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11 mark

Xylitol is an artificial sweetener used in toothpastes and chewing gum to improve their taste without impairing dental hygiene.10-2-m-q1-ib-chemistry-mcqs

Which functional groups could be produced if Xylitol is oxidised under suitable conditions?

 

1

              alkene

2

              aldehyde

3

              carboxylic acid

4

              ketone

  • 1 only

  • 2 only

  • 2, 3 and 4

  • 2 and 4

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21 mark

Which alcohol is not likely to have a fragment at m/e at 43 in its mass spectrum?

  • (CH3)2CHCH2OH

  • CH3CH(OH)CH2CH2CH3

  • CH3CH2CH2CH2OH

  • CH3CH2CH(OH)CH3

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31 mark

Which of the compounds shown below is likely to have a fragment at m/e = 45 in its mass spectrum?

11-1-mcq-q2-medium-ib-chemistry

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41 mark

Chlorine has two isotopes 35Cl and 37Cl.  Assuming in the molecule C4H6Cl4 there is only one hydrogen and one carbon isotope, how many molecular ion peaks will be seen in its mass spectrum?

  • 5

  • 4

  • 3

  • 2

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51 mark

Bromine exists as two isotopes 79Br and 81Br, which are found in almost equal abundance. 

Which of the following statements is correct?

  • 79Br is more reactive than 81Br

  • The mass spectrum of C3H7Br has two molecular ion peaks at 122 and 124

  • The atomic radius of 79Br is less than the atomic radius of 81Br

  • The first ionisation energy of 79Br is less than the first ionisation energy of 81Br

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61 mark

Which alcohol is likely to have a fragment ion at m/e = 31 in its mass spectrum?

  • CH3)2CHCH2OH

  • CH3CH(OH)CH2CH2CH3

  • CH3CH2CH2C(OH)(CH3)2

  • CH3CH2CH(OH)CH3

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71 mark

Which pair of compounds would you expect to both have a singly charged peak at m/e = 29 in the mass spectrum? 

  • propan-1-ol and propanal

  • propanal and propanone

  • propan-2-ol and propanal

  • propan-1-ol and propan-2-ol

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81 mark

The infrared spectrum of a compound is shown below.

d6mgC1_0_11-1-mcq-q7-medium-ib-chemistry

Use the infrared absorptions, in wavenumbers, to identify the compound 

bond

wavenumber range/ cm-1

O−H (alcohol)

3750 – 3200

C−H (alkane)

2962 – 2853

C−H (aldehyde)

2900 – 2820 and 2775 – 2700

C═O (aldehyde or ketone)

1740 - 1680

 

Which compound is shown by the infrared spectrum?

  • propan-1-ol

  • propan-2-ol

  • propanal

  • propanone

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91 mark

Which of the ketones listed would not be expected to have a peak in its mass spectrum at m/e = 57?

  • hexan-3-one, CH3CH2CH2COCH2CH3

  • pentan-3-one, CH3CH2COCH2CH3

  • 3-methylbutanone, (CH3)2CHCOCH3

  • butanone, CH3CH2COCH3

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101 mark

Which of the following statements about the mass spectrum of CH3Br is correct?

  • There is one peak for the molecular ion with an m/e value of 44.

  • There is one peak for the molecular ion with an m/e value of 95.

  • The last two peaks have abundances in the ratio 3:1 and occur at m/e values of 94 and 96.

  • The last two peaks are of equal size and occur at m/e values of 94 and 96.

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111 mark

Below is a 1H NMR spectrum for an unknown organic compound. The relative areas under the peaks are labelled

11-1-mcq-q10-medium-ib-chemistry

Which of the following compounds could give this spectrum?

  • propan-1-ol, CH3CH2CH2OH

  • propan-2-ol, CH3CH(OH)CH3

  • methyoxyethane, CH3OCH2CH3

  • pentan-2-one, CH3CH2CH2COCH3

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121 mark

How many structural isomers are there of tribromopropane, C3H5Br3?

  • 4

  • 5

  • 6

  • 7

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131 mark

How many isomeric esters have the molecular formula C5H10O2?

  • 4

  • 5

  • 9

  • 7

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141 mark

Which features about the members of a homologous series are correct?

  1.  all members have the same general formul
  2.  the members have similar chemical properties
  3.  the members show a gradual change in physical properties

  • I and II only

  • I and III only

  • II and III only

  • I, II and III

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151 mark

Octane is a component of petrol or gasoline. Which of the following molecules could be an isomer of octane?

  • CH3CH2CHCHCHCH2(CH3)2

  • (CH3)2CHCH(CH2)2(CH3)2

  • CH3(CH2)5CH3

  • CH3CHCHCH(CH2)2(CH3)2

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161 mark

Give the name of the following molecule10-1-m-q5-mcqs-ib-chemistry

  • 2,4,4,4-trimethylethylbutane

  • 3,3,5-trimethylhexane

  • 2,4,4-trimethylhexane

  • 1,1,3,3-tetramethylpentane

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171 mark

How many branched-chain isomers are there which have the molecular formula C5H12?

  • 2

  • 3

  • 4

  • 5

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181 mark

Study the diagram below and determine which of the three statements are correct

10-1-m-q8-mcqs-ib-chemistry

  1.   A suitable name is hex-4-ene
  2.   The empirical formula is CH2
  3.    It is an isomer of cyclohexane

  • I and II only

  • I and III only

  • II and III only

  • I, II and III

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191 mark

Which of the molecules shown below contains an aldehyde functional group?

  • CH3CH2CH2OOCH3 

  • CH3CH2CH2COCH3

  • CH3CH2OCH2CH3

  • CH3CH2CH2CH2CHO

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201 mark

Which of the halogenoalkanes shown below contains a tertiary carbon atom?

  • CH3CH2CH2Cl

  • CH3CH2CH(CH3)Br

  • C(CH3)3Cl

  • CH3CHBrCH2CH3

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211 mark

What would be the name of the following compound using IUPAC rules?

10-1-m-q10-mcqs-ib-chemistry

  • pentane

  • ethylpropane

  • 2-methylbutane

  • 3-methylbutane

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221 mark

Which two molecules are cis-trans isomers of each other?

q1_16-2_ib_hl_medium_mcq

  • X and Z

  • X and Y

  • W and Y

  • W and Z

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231 mark

What is this molecule called?
q2_20-3_ib_hl_medium_mcq

  • Z-2-bromo-1-chloro-2-fluoroethene

  • E-2-bromo-1-chloro-2-fluoroethene

  • Z-1-bromo-2-chloro-1-fluoroethene

  • E-1-bromo-2-chloro-1-fluoroethene

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241 mark

Which molecule has optical isomers?

  • 2-bromobutane

  • 1,3-dibromopropane

  • 2-chloro-2-methylpropane

  • 3-bromopentane

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251 mark

What is the name of this molecule?
q4_20-3_ib_hl_medium_mcq

  • cis-3-methyl-3-hexene

  • trans-4-methyl-4-hexene

  • cis-3-methyl-2-hexene

  • trans-3-methyl-2-hexene

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261 mark

Which is true about stereoisomerism?

  • But-1-ene has E/Z isomers

  • Butan-2-ol has two enantiomers

  • But-1-ene and but-2-ene are cis-trans isomers

  • Butan-1-ol and butan-2-ol are optical isomers

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