NAME:_____________________________________________________ CLASS: __________
CHEMISTRY
SEMESTER 3 (962/3)
SECTION A
[15 marks]
Answer all questions in this section
1. Naphthalene, C10H8 is an active component in mothballs. Its structural formula is shown
below
A) 5 B) 6 C) 10 D) 11
2. Which molecule has carbon atoms with sp hybrid orbitals?
A) CH=CH B) CH2=CH2 C) CH3CH3 D) C6H6
3. Which compound does not correspond correctly to its functional group?
Compound Functional group
A C6H5CH2OH -OH
B CH3COOH O
||
-C- O -
C CH3CONH2 O
||
- C – NH2
D CH3CHO O
||
- C-H
4. An organic compound contains carbon, hydrogen and oxygen. The complete combustion
of 16.5g of the liquid gives 31.6g of carbon dioxide and 19.3g of water. What is the
empirical formula of the organic liquid?
A) CH4O B) C2H4O C) C2H6O D) C3H8
5. The following organic compounds show stereoisomerism.
I CH3CH2CH=C(CH3)CH2CH3
II HOCH2 – CH – C(CH3)2CH=CH2
|
CHO
III CH3 – CH=C – CH2CH3
|
CH2CH2CH3
What type of stereoisomerism is shown by each compound?
I II III
A Geometrical Geometrical Optical
B Geometrical Optical Geometrical
C Optical Geometrical Optical
D Optical Optical Geometrical
6. The mechanism of chlorination of methane involves several steps. The propagation step
for this mechanism is
A Cl · + CH4 CH3Cl + H·
B Cl · + CH3· CH3Cl
C CH3· + Cl2 CH3Cl + Cl ·
D CH4 CH3· + H·
7. A cyclohexane, C6H12, undergoes a free radical substitution reaction with bromine. What
is number of propagation steps involved in this reaction to form C6Br12
A) 6 B) 12 C) 18 D) 24
8. A cracking process is carried out on dodecane, C12H26, at 6000C and high pressure. Which
compounds are in this process?
A) Ethane, butane and hexene
B) Ethane, propane and heptane
C) Ethene, propene and heptane
D) Ethene, butane and hexane
9. Ethene undergoes addition reaction due to the presence of C=C bond. Which is not true
of the bromination of ethene?
A) The C=C bond readily accepts an electrophile
B) Brominium ion is formed as an intermediate
C) A π bond is converted to a σ bond
D) The product formed is 1,1 – dibromoethane
10. Alkenes undergo electrophile addition reaction. The following alkenes react with
bromine in CCl4 to form optically active compounds excepts
A CH3CH=CClCH3
B (CH3)2C=CHCl
C CH3CH=CBrCH2CH3
D Cl2C=CBrCH2CH3
11. An organic compound undergoes oxidation and addition reaction with acidified
potassium permanganate solution under different condition. The compound is
B
CH3
C C(CH3)2OH
D COCH3
12. P and Q are 2 hydrocarbons with empirical formula CH2 and CH respectively. Under
same conditions, P decolorizes bromine water while Q does not. Which mechanism are
correct the reactions of P and Q?
P Q
A Electrophilic addition Electrophilic substitution
B Electrophilic addition Nucleophilic substitution
C Nucleophilic substitution Nucleophilic substitution
D Electrophilic substitution Electrophilic substitution
13. Which statement is true of cyclohexane, cyclohexene and benzene?
A) The three compounds undergo addition reaction
B) The three compounds have the same bond length
C) The three compounds undergo Friedel-Crafts alkylation
D) The three compounds undergo halogenation under different conditions
14. Which statement about the reaction between methylbenzene and chlorine in the presence
of light is true?
A) The reaction is a free radical addition reaction
B) Hydrogen chloride is formed in the termination step
C) (Chloromethyl)benzene is formed in the first propagation step
D) 1 - chloro – 4 – methylbenzene is one of the products of the reaction
15. The structure formula of toluene and cyclohexene are shown below
CH3
Toluene Cyclohexene
Which reagent can react with both compounds?
A) O3 B) HBr C) Br2 in CCl4 D) Hot KMnO4, OH-
SECTION B [15 marks]
Answer all questions in this section
16. The structural formulae of 2 compounds are shown below [STPM2014]
H H
H3C C COOH H3C C COOH
H Cl
Propanoic Acid X
(a) Name X using IUPAC nomenclature
……………………………………………………………………………………………[1mark]
(b) (i) Which compounds is more acidic in aqueous solution?
……………………………………………………………………………………………[1mark]
(ii) Explain your answer in (b)(i)
………………………………………………………………………………………………………
……………………………………………………………………………………………[2marks]
(c) X exhibits optical activity
(i) What is meant by optical activity?
……………………………………………………………………………………………[1mark]
(ii) Draw its optical isomers
[2marks]
17. (a) 3 – methylcyclohexene yields more than on product when it reacts with hydrogen
bromide. [STPM2013]
(i) Draw the structure of the products
[2marks]
(ii) Suggest a reagent which can be used to differentiate 3 – methylcyclohexene from
3 – methylcyclohexane
……………………………………………………………………………………[1mark]
(b) The following scheme shows the chemical reactions starting from benzene.
CH2CH3
Step W KMnO4 / H+
Br2 / uv
Y (Major product)
(i) State the reagent in step W
………………………………………………………………………………………….[1mark]
(ii) Name the mechanism involved in the reaction
…………………………………………………………………………………………[1mark]
(iii) Write an equation for the formation of the electrophile in step W.
………………………………………………………………………………………….[1mark]
(iv)Draw the structural formulae of compounds X and Y in the boxes provided above
[2marks]
SECTION C [ 30 marks]
Answer two questions only in this section
18. (a) 2 organic compounds, P and Q are formed when 2 – pentene reacts with Hydrogen
Bromide. P is an optically active compounds [STPM2015]
(i) Show how P and Q are formed and determine their structural formulae. [7marks]
(ii) Draw the 3-dimensional formulae for the optical isomers of P. [2marks]
(b) 2 – chloro – 2- methylpentane reacts with an aqueous solution of sodium hydroxide to
form W, and an ethanolic solution of sodium hydroxide to form X and Y
(i) Name the type of reactions involved [2marks]
(ii) Draw the structural formulae of W, X amd Y [3marks]
(iii) Name the mechanism involved in the formation of W [1mark]
19. Bromination of ethylbenzene in the presence of ultraviolet light yields monobrominated
products P and Q. P rotates plane – polarized light but Q does not. When P and Q are
refluxed separately with an aqueous of sodium hydroxide, R and S are formed
respectively. [STPM2016]
(a) Determine the structural formulae of P, Q, R and S. [4marks]
(b) Describe the mechanism for the formation of P and Q [6marks]
(c) Determine the major products of the reaction [3marks]
(d) Suggest a chemical test to differentiate between R and S [2marks]
20. (a) Cycloalkane and alkenes have the same general formulae. The structural formula of a
cycloalkane is shown below. [STPM2015]
H 3C CH3
(i)State the types of isomerism shown by the cycloalkane above [2marks]
(ii)Write the structural formulae of an alkene, C7H14, that exhibits the isomerism in (i) and draw
all the isomers [3marks]
(iii)Suggest a chemical test to distinguish cycloalkane from the alkene in (ii). State the
observation and write the reaction equation involved. [3marks]
(b) Isopropylbenzene is an example of an alkylbenzene which can react with CH3Cl / FeCl3.
Draw the mechanism for the reaction and name the type of reaction. [7marks]
-END OF QUESTION-
Prepared by Checked by Comfirmed by
Yong Kui Len Kardianah Kaling Chang Oi Khyun
Chemistry teacher Head of Chemistry Unit Head of Science Department
