309Doc Scientia - IEB Senior Chemistry Textbook and Workbook Book 2

EXAM QUESTIONSUNIT 1: Organic molecules

Multiple-choice questions

Four possible answers are given for the following questions. Each question has only ONE correct answer.Choose the correct answer and mark the applicable LETTER with a cross (X).1. Which one of the following is NOT a property of carbon that enables it to be the building block of organic chemistry? A. It forms strong covalent bonds to other atoms. B. It forms weak induced dipole forces with other atoms. C. It has a valency of four in a tetrahedral arrangement. D. It can form bonds to itself.2. Which one of the following molecular formulae represents an alkene? A. C15H32 B. C15H28 C. C21H44 D. C18H363. Which one of the following reactions will NOT take place with an alkene? A. Hydrohalogenation B. Combustion C. Hydrogenation D. Dehydration4. Which one of the following organic compounds has the weakest intermolecular forces? A. Heptane B. Heptan-1-ol C. 2,2-dimethylpentane D. Heptanoic acid5. What is an atom or group of atoms that forms the centre of chemical activity in an organic compound called? A. Isomer B. Homologous series C. Reactivity core D. Functional group6. Which one of the following organic compounds is an unsaturated hydrocarbon? A. C2H6 B. C3H6 C. CH3COOH D. CH47. The IUPAC name of the organic compound given is: A. 2-ethyl-3-methylbutane B. 3-ethyl-2-methylbutane C. 2-ethyl-1,1-dimethylpropane D. 2,3-dimethylpentane8. Which one of the following pairs of organic molecules are structural isomers?

CH3CHCHCH3

CH2CH3

CH3

A. CH3CH2CH2OH and CH3C-CH2CH3

O

B. CH3-CH-CH3 and CH3-CH-OH

OH CH3

C. CH3-CH2-C-OH and CH3-O-C-CH3

O O

D. CH2Cℓ-CH2Cℓ and CH3-CHBr2

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9. The structural formula of an organic compound is shown alongside: The IUPAC name for this compound is: A. 2,3-dimethylhept-5-ene. B. 5,6-dimethylhept-2-ene C. 2,3-dimethylhept-2-ene. D. 5,6-dimethylhept-3-ene.10. The molecular formula for propene is: A. C3H9. B. C3H8. C. C3H6. D. C3H5.11. Which ONE of the following compounds has a structural isomer? A. Ethane B. Bromoethane C. Chloroethane D. 1,2-dibromoethane12. Which ONE of the following compounds is saturated? A. B.

C. D.

13. Study the following structural formula of an organic compound:

Which ONE of the following is the correct IUPAC name for this compound? A. 2-ethylpentane B. 4-ethylpentane C. 3-methylhexane D. 4-methylhexane14. How many structural isomers does the compound with molecular formula C4H10 have? A. 1 B. 2 C. 3 D. 4

HCC CCH

BrH HH

HH HH

HCC CCH

HHH

HHH

HCC CCH

HH

BrH

HCCC

H

C

H

C

C

CH

H H HH HH

H HH H

H

H

C H

H

C

C

H

H

H

C

H

CH3 CH2 CH3CH CHCH CH

CH3

CH3

ORGANIC COMPOUNDSExam Questions

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15. Study the following compound:

The IUPAC name for the compound is: A. methylethyl-2-ethylpentane. B. 3-ethyl-2,3-dimethylhexane. C. 2-ethyl-2-propylpentane. D. 2-ethyl-2-methyl-2-propylbutane.16. Which type of isomers are 1,2-dibromoethane and 1,1-dibromoethane? A. Halogen isomers B. Functional isomers C. Positional isomers D. Chain isomers17. Which one of the following compounds is an alkene with a side chain? A. CH3CH2CH(CH3)CH2CH3 B. CH3CH2CHCHCH2CH3 C. CH3CH2CHC(CH3)CH3 D. CH2CH2CH(CH3)CH2CH218. Which one of the following molecules is a structural isomer of ethyl butanoate? A. 3-methylpentanol B. 3,3-dimethylbutanoate C. Hexanoic acid D. 3-methylpentan-2-ol

19. When the group is present in a compound, it could probably have the following IUPAC name: A. carboxylic acid. B. 1-propanol. C. alkene. D. methyl ethanoate.20. What does the following represent?

A. methyl butane

B. pentane

C. dimethylpropane

D. ethylmethyl etane

21. Which ONE of the following cannot be an ester or a carboxylic acid? A. C3H6O B. C3H4O2 C. CH2O2 D. C2H4O2

H

H

C

C

C

C

C

H

C

H

H H

H

H

C

H

C

C

CH

H H

H

H

HH

HH H

H

HH

C

O

O

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22. Which of the following are structural isomers?

I II III

23. The condensed structural formula of an organic structure is illustrated:

What is the correct IUPAC name for this compound? A. 5,6-dibromooctane B. 4-bromo-5-bromo-5-propylpentane C. 3,4-dibromooctane D. 2-bromo-1-bromo-1-propylpentane24. An organic compound that is always found in alcoholic drinks is: A. CH3OH. B. C2H5OH. C. C6H10. D. C6H5(CH3).

Contextual questions

1 The letters A to F in the table below represent six organic compounds:

A. Buta-1,2-diene B. ethyl propanoate C. Propan-1-ol

D. E. F.

1.1 Write down the LETTER representing the following:1.1.1 An alkane 1.1.2 An alcohol1.2 Write down the IUPAC name of:1.2.1 E; 1.2.2 D.1.3 Write down the structural formula of:1.3.1 C; 1.3.2 A;1.3.3 a chain isomer of E; 1.3.4 a functional isomer of B.

CH2 CH2 CH2

CH2 CH3

CH

CH

Br

Br

H3C

C C C C HH

H HHH

H HHH

CCH3 CH3

CH3

OH

CH3(CH2)3(CH)2CH2Br

A. Only I and IIB. Only II and IIIC. Only I and IIID. I, II and III

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2 Complete the following table:

Series General formula Structural formula IUPAC nameAlkane CnH2n + 2 2.1 2,3-dimethyl butane

2.2 CnH2n 2.3

3.1 Draw and give the IUPAC name of a functional isomer of propanoic acid.3.2 Name and discuss the differences in physical properties between propanoic acid and the functional isomer in Question 3.1.

4 The alkane consisting of four carbon atoms has two structural isomers.4.1 Define the term structural isomer.4.2 Draw the structural formula of the branched isomer of this alkane.

5 Consider the organic compounds represented by the letters A–D:

A. CH3CH2–Br B. C8H18

C.D. CH3CH2CH2CH2CH3

5.1 Compound A is prepared from a substitution reaction involving an alkane. Write down the name of this alkane.5.2 Give the IUPAC name for the ester formed when compound C reacts with ethanol in the presence of concentrated sulfuric acid.5.3 Write down the structural formula for a chain isomer of D, which has three C atoms in its longest chain. Give the name of this isomer.5.4 Give one use for compound B. Northern Cape, 2008

H

H

CC C

C

C

CH

H

H

HH

HH HH

C

O

CH3HO