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Multiple Choice Questions (MCQ) topic quiz
Colour by design
Instructions and answers for teachersThese 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 ActivityThis 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 OutcomesThis Lesson Element relates to the specification learning outcomes CD(c), CD(e), CD(g), CD(i), CD(k), CD(m), CD(n).
IntroductionMultiple 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.
Version 1 1 © OCR 2016
Multiple Choice Questions (MCQ) topic quiz - answers1. 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. 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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B
A
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
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
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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B
A
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
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
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 ofpropan-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. 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
C
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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
Version 1 10 © 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
Version 1 11 © 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
Version 1 12 © 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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