Download OCR A Level Chemistry B (Salters) Multiple Choice Questions Quiz

Multiple Choice Questions (MCQ) topic quiz
Colour by design
Instructions and answers for teachers
These instructions cover the student activity section which can be found on page 10. This
Lesson Element supports OCR A Level Chemistry B (Salters).
When distributing the activity section to the students either as a printed copy or as a
Word file you will need to remove the teacher instructions section.
The Activity
This Lesson Element is a teaching and learning resource containing 10 multiple choice
questions (MCQs) on the theme of colour by design. Some questions might require synoptic
thinking, using knowledge and ideas from various topics across the full A Level content.
This resource can be used to test and consolidate understanding at the end of a topic or to
revisit and refresh knowledge at a later point in the course.
Learning Outcomes
This Lesson Element relates to the specification learning outcomes CD(c), CD(e), CD(g),
CD(i), CD(k), CD(m), CD(n).
Introduction
Multiple choice questions allow rapid coverage of a wide range of sub-topics.
Contrary to a widespread belief among students, multiple choice questions are not
necessarily easy – they can be easy, moderate or difficult.
The questions are written so that the incorrect answers are plausible distractors based on
common errors or misconceptions.
The questions in this quiz cover topics mainly from specification sections:
Colour by design.
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Multiple Choice Questions (MCQ) topic quiz - answers
1.
Which term best describes the reaction between benzene and chloromethane in the
presence of aluminium chloride?
A
addition
Benzene rings do not undergo addition
reactions readily, unlike other unsaturated
compounds.
B
alkylation
Correct answer: The reaction results in the
substitution of a methyl group onto the ring.
C
nucleophilic substitution
The reaction is an electrophilic substitution
since the attacking methyl group carries a
positive charge.
D
reduction
The learner is perhaps confusing the
aluminium chloride catalyst with the reducing
agent lithium aluminium hydride.
Your answer
2.
B
Benzene can undergo a substitution reaction in the presence of concentrated nitric
acid and concentrated sulfuric acid.
What is the electrophile in this reaction?
A
NO2+
Correct answer: The nucleophile is produced
by the loss of hydroxide from the HNO3
molecule to make water with a proton donated
by H2SO4 (nitric acid is a weaker acid than
sulfuric).
B
NO2+
The learner has perhaps rote-learned the
name of the nucleophile and so is unable to
properly distinguish between the answers in A
and B.
C
NO3+
The learner is trying to turn nitric acid into an
electrophile without an appreciation of the
chemistry involved.
D
SO3
The learner is confusing nitration with
sulfonation due to the presence of sulfuric acid.
Your answer
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A
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3.
How do the boiling points of aldehydes compare with those of alkanes and alcohols
of similar molecular mass?
A
alcohol < aldehyde < alkane
This is the opposite order and the learner
therefore may have misread the question.
B
aldehyde < alkane < alcohol
The learner knows that alcohols have the
highest boiling point but perhaps doesn’t
appreciate the significance of the permanent
dipole interactions in aldehydes.
C
alkane < alcohol < aldehyde
The learner knows alkanes have the lowest
boiling point but perhaps thinks that aldehydes
are also capable of forming hydrogen bonds.
D
alkane < aldehyde < alcohol
Correct answer: Alkanes have only
instantaneous dipole–induced dipole bonds;
aldehydes also have permanent dipole–
permanent dipole bonds and alcohols can form
hydrogen bonds between molecules.
Your answer
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D
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4.
Which chemical test could be used to easily distinguish between two isomeric
carbonyl compounds with the formula C3H6O?
A
aqueous sodium carbonate
solution
Sodium carbonate is a suitable test for
identifying the presence of a carboxylic acid,
but both molecules only contain one oxygen
atom.
B
bromine water
Bromine water alone would not react readily
with either molecule (both could react with
bromine in the presence of an acid catalyst).
The learner is trying to distinguish between
saturated and unsaturated compounds but in
both molecules the double bond is a C=O not
C=C.
C
hydrogen cyanide
Both molecules could react with hydrogen
cyanide so there would be no visible
difference.
D
Tollens’ reagent
Correct answer: Tollens’ reagent is an
oxidising agent and so would only react with
the aldehyde – ketones cannot be oxidised
further.
Your answer
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D
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5.
Which reagent would not be able to convert ethanal to ethanoic acid?
A
acidified potassium dichromate
(with warming)
Aldehydes are readily oxidised by
dichromate.
B
aluminium chloride
Correct answer: Aluminium chloride is a
catalyst for electrophilic substitution reactions
of benzene and could not oxidise an
aldehyde.
C
Fehling’s solution (with warming)
Although more commonly used as a test for
aldehydes, the basis of the test is the ability
of the aldehyde to be oxidised further to form
a carboxylic acid.
D
Tollens’ reagent
See C – Tollens’ is an oxidising agent.
Your answer
6.
Which would result in a shorter retention time for a gas–liquid chromatography
column?
A
a more volatile sample
Correct answer: A more volatile sample
would spend more time in the mobile gas
phase and thus move through the column
faster.
B
a longer column
A longer column would take longer for the
molecules to pass through – the learner has
perhaps misread the question.
C
a sample which is more soluble in
the stationary phase than the
mobile phase
Again the learner has perhaps misread the
question or does not understand the
significance of the two phases. A sample
which spends more time dissolved in the
stationary phase will take longer to travel
through the column.
D
decreasing the temperature
Decreasing the temperature will make the
sample less likely to turn into a gas, causing
it to spend less time in the mobile phase.
Your answer
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A
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7.
Which diagram correctly shows the first step in the nucleophilic addition of cyanide to
a carbonyl compound?
A
B
C
D
A
This is a common mistake as learners are so used to seeing nitrogen as a
nucleophilic atom.
B
Here the learner is confusing nucleophilic addition with electrophilic addition
as this is similar to the first stage of addition of electrophiles to alkenes.
C
Here the learner has correctly identified the negative carbon atom as the
nucleophile but is confused about the subsequent electron movement
required to form a stable intermediate.
D
Correct answer: The negative carbon (formed by dissociation of the HCN
molecule) acts as a nucleophile; in order to form a new bond with the
carbonyl carbon there must be concomitant movement of a pair of electrons
onto the oxygen atom.
Your answer
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D
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8.
Which statement about coloured organic compounds is correct?
A
Absorption of red light is more
common than absorption of blue
light.
In fact the opposite is true – the learner is
perhaps aware that most coloured organic
compounds are at the red end of the
spectrum but is not associating this with the
absorption of complementary colours of light.
B
All aromatic compounds are
coloured.
Aromatic compounds only absorb visible light
when a high degree of delocalisation is
present – the mere presence of a benzene
ring is not sufficient.
C
Energy levels become closer
together the greater the degree of
delocalisation.
Correct answer: Greater delocalisation
results in lower energy levels which become
closer together and thus more likely to allow
absorption of visible light wavelengths.
D
Only alternating C=C and C–C
bonds can take part in
delocalisation of electrons.
Lone pairs from nitrogen and oxygen atoms
can also take part in delocalisation.
Your answer
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C
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9.
Which statement about triglycerides is true?
A
They are water-soluble due to the
presence of a charged phosphate
group.
The learner is confusing triglycerides with
phospholipids.
B
They are esters of
propan-1,1,1-triol.
The learner has not thought through the
structure of glycerol – it is propan-1,2,3-triol.
C
They may react with bromine in
an addition reaction.
Correct answer: Many fatty acid chains
contain some C=C bonds which will react
readily with bromine.
D
The presence of cis C=C bonds in
the fatty acid chains leads to a
higher melting point.
The opposite is true – cis C=C bonds create
‘kinks’ in the fatty acid chains which push the
chains apart and allow fewer instantaneous
dipole–induced dipole bonds to form,
resulting in a lower melting temperature.
Your answer
10.
C
Which statement(s) is/are evidence that supports the delocalised structure of
benzene (rather than the Kekulé structure)?
Statement 1: The enthalpy of hydrogenation for benzene is much more exothermic
than predicted for 1,3,5-cyclohexatriene.
Statement 2: The molecule does not readily undergo addition reactions.
Statement 3: The X-ray crystal structure shows all the carbon–carbon bond lengths
to be equal.
A
1, 2 and 3
Statement 1 is not true – the enthalpy of
hydrogenation of benzene is less exothermic
than predicted for the triene structure, due to
the increased stability of the aromatic system.
B
only 1 and 2
Statement 2 is true (due to increased stability
of the aromatic system) but Statement 1 is
incorrect, as explained above.
C
only 2 and 3
Correct answer: Statement 3 is true as it
provides evidence that the bonds do not
alternate between double and single bonds.
Statement 2 is also true as explained above.
D
only 1
See above explanations – Statement 1 is the
only false statement.
Your answer
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C
© OCR 2016
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Multiple Choice Questions (MCQ) topic quiz
Colour by design
Learner Activity
1.
Which term best describes the reaction between benzene and chloromethane in the
presence of aluminium chloride?
A
addition
B
alkylation
C
nucleophilic substitution
D
reduction
Your answer
2.
Benzene can undergo a substitution reaction in the presence of concentrated nitric
acid and concentrated sulfuric acid.
What is the electrophile in this reaction?
A
NO2+
B
NO2+
C
NO3+
D
SO3
Your answer
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© OCR 2016
3.
How do the boiling points of aldehydes compare with those of alkanes and alcohols of
similar molecular mass?
A
alcohol < aldehyde < alkane
B
aldehyde < alkane < alcohol
C
alkane < alcohol < aldehyde
D
alkane < aldehyde < alcohol
Your answer
4.
Which chemical test could be used to easily distinguish between two isomeric carbonyl
compounds with the formula C3H6O?
A
aqueous sodium carbonate solution
B
bromine water
C
hydrogen cyanide
D
Tollens’ reagent
Your answer
5.
Which reagent would not be able to convert ethanal to ethanoic acid?
A
acidified potassium dichromate (with warming)
B
aluminium chloride
C
Fehling’s solution (with warming)
D
Tollens’ reagent
Your answer
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© OCR 2016
6.
Which would result in a shorter retention time for a gas–liquid chromatography column?
A
a more volatile sample
B
a longer column
C
a sample which is more soluble in the stationary phase than the mobile phase
D
decreasing the temperature
Your answer
7.
Which diagram correctly shows the first step in the nucleophilic addition of cyanide to a
carbonyl compound?
A
B
C
D
Your answer
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© OCR 2016
8.
Which statement about coloured organic compounds is correct?
A
Absorption of red light is more common than absorption of blue light.
B
All aromatic compounds are coloured.
C
Energy levels become closer together the greater the degree of delocalisation.
D
Only alternating C=C and C–C bonds can take part in delocalisation of electrons.
Your answer
9.
Which statement about triglycerides is true?
A
They are water-soluble due to the presence of a charged phosphate group.
B
They are esters of propan-1,1,1-triol.
C
They may react with bromine in an addition reaction.
D
The presence of cis C=C bonds in the fatty acid chains leads to a higher
melting point.
Your answer
10.
Which statement(s) is/are evidence that supports the delocalised structure of benzene
(rather than the Kekulé structure)?
Statement 1: The enthalpy of hydrogenation for benzene is much more exothermic than
predicted for 1,3,5-cyclohexatriene.
Statement 2: The molecule does not readily undergo addition reactions.
Statement 3: The X-ray crystal structure shows all the carbon–carbon bond lengths to be
equal.
A
1, 2 and 3
B
only 1 and 2
C
only 2 and 3
D
only 1
Your answer
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© OCR 2016