GRADE 12
CHEMISTRY
MULTIPLE-CHOICE EXAMINATION
QUESTIONS
A PREPARATION GUIDE
,
, GRADE 12
CHEMISTRY
MULTIPLE-CHOICE EXAMINATION
QUESTIONS
A PREPARATION GUIDE
, GENERAL GUIDELINES WHEN ANSWERING MULTIPLE CHOICE QUESTIONS
Don't be afraid of multiple-choice questions. Here are a few tips to answer them.
1. Do not spend more than about 30 minutes on the multiple-choice questions.
2. Start by carefully reading the sub-questions (1.1, 1.2, etc.) and pay attention to the keywords.
3. Aso pay attention to words that are in capital letters or otherwise emphasised. This is always
important, even in the rest of the paper. The examiner wants you to focus on the emphasised
words.
4. Decide whether you are required to recall or use a fact, phenomenon, definition, unit or formula.
5. Use the process of elimination. Eliminate all the answers you know are incorrect, then focus on
the remaining answers. Not only does this strategy save time, it greatly increases your
likelihood of selecting the correct answer.This is particularly helpful when the answers or
options are very close to each other.
6. Never leave a multiple-choice question unanswered. If you do not know the answer, even after
trying the process of elimination, then guess!
7. Answers supplied to the questions below demonstrate how to solve multiple choice questions
that involve more than one step. A seemingly difficult chemistry multiple choice question might
be very easy to solve if you follow the steps.
EXAMPLE 1
The condensed structural formula of an organic compound is given below.
CH3
Cℓ CH2 CH CH CH3
CH2
CH3
Which ONE of the following is the correct IUPAC name of this compound?
A 1-chloro-2,3-dimethylbutane B 1-chloro-2,3-dimethylpentane
C 1-chloro-3-ethyl-2-methylbutane D 5-chloro-3,4-dimethylpentane
Solution:
• All bonds are single bonds and the compound has a chlorine substituent – thus it is a chloroalkane/
haloalkane.
• Determine the longest chain that contains the halogen. The straight chain has 4 C atoms, but when counting
3 C atoms from the halogen and then 2 C atoms down, the longest chain has 5 C atoms. Therefore the
compound is a pentane with a chloro and two methyl (1 C atom each) substituents i.e.
chlorodimethylpentane.
• Answers A and C (both butane) are eliminated. The choice is now between B and D.
• Count from the side giving the substituents (halogen and alkyl) the lowest number. No preference is given
to the halogen substituent.
• When C atoms are numbered from the C atom bonded to the chlorine, the compound is 1-chloro-2,3-
dimethylpentane and from the other side it is 5-chloro-3,4-dimethylpentane. 1,2,3 is smaller than 5,3,4.
• Answer: B
EXAMPLE 2
Consider the following hypothetical reaction that reached equilibrium in a closed container at 450 °C:
XY(s) ⇌ X(g) + Y(s) ΔH > 0
Which ONE of the following changes will NOT affect the equilibrium position?
A Increase in temperature
B Increase in the amount of Y(s)
C Decrease in pressure at constant volume
D Increase in the volume of the container
CHEMISTRY
MULTIPLE-CHOICE EXAMINATION
QUESTIONS
A PREPARATION GUIDE
,
, GRADE 12
CHEMISTRY
MULTIPLE-CHOICE EXAMINATION
QUESTIONS
A PREPARATION GUIDE
, GENERAL GUIDELINES WHEN ANSWERING MULTIPLE CHOICE QUESTIONS
Don't be afraid of multiple-choice questions. Here are a few tips to answer them.
1. Do not spend more than about 30 minutes on the multiple-choice questions.
2. Start by carefully reading the sub-questions (1.1, 1.2, etc.) and pay attention to the keywords.
3. Aso pay attention to words that are in capital letters or otherwise emphasised. This is always
important, even in the rest of the paper. The examiner wants you to focus on the emphasised
words.
4. Decide whether you are required to recall or use a fact, phenomenon, definition, unit or formula.
5. Use the process of elimination. Eliminate all the answers you know are incorrect, then focus on
the remaining answers. Not only does this strategy save time, it greatly increases your
likelihood of selecting the correct answer.This is particularly helpful when the answers or
options are very close to each other.
6. Never leave a multiple-choice question unanswered. If you do not know the answer, even after
trying the process of elimination, then guess!
7. Answers supplied to the questions below demonstrate how to solve multiple choice questions
that involve more than one step. A seemingly difficult chemistry multiple choice question might
be very easy to solve if you follow the steps.
EXAMPLE 1
The condensed structural formula of an organic compound is given below.
CH3
Cℓ CH2 CH CH CH3
CH2
CH3
Which ONE of the following is the correct IUPAC name of this compound?
A 1-chloro-2,3-dimethylbutane B 1-chloro-2,3-dimethylpentane
C 1-chloro-3-ethyl-2-methylbutane D 5-chloro-3,4-dimethylpentane
Solution:
• All bonds are single bonds and the compound has a chlorine substituent – thus it is a chloroalkane/
haloalkane.
• Determine the longest chain that contains the halogen. The straight chain has 4 C atoms, but when counting
3 C atoms from the halogen and then 2 C atoms down, the longest chain has 5 C atoms. Therefore the
compound is a pentane with a chloro and two methyl (1 C atom each) substituents i.e.
chlorodimethylpentane.
• Answers A and C (both butane) are eliminated. The choice is now between B and D.
• Count from the side giving the substituents (halogen and alkyl) the lowest number. No preference is given
to the halogen substituent.
• When C atoms are numbered from the C atom bonded to the chlorine, the compound is 1-chloro-2,3-
dimethylpentane and from the other side it is 5-chloro-3,4-dimethylpentane. 1,2,3 is smaller than 5,3,4.
• Answer: B
EXAMPLE 2
Consider the following hypothetical reaction that reached equilibrium in a closed container at 450 °C:
XY(s) ⇌ X(g) + Y(s) ΔH > 0
Which ONE of the following changes will NOT affect the equilibrium position?
A Increase in temperature
B Increase in the amount of Y(s)
C Decrease in pressure at constant volume
D Increase in the volume of the container
