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Question 1
Which class of compound is an example of a carbonyl compound?
a) alcohol
b) carboxylic acid
c) alkene
d) alkane
Question 2
Which molecule is an example of a ketone?
a) Ethanal (Acetaldehyde)
b) Ethanoic anhydride (Acetic anhydride)
c) Propan-2-one (acetone)
d) Propanamide
Question 3
Which molecule is an example of an amide?
a) Ethanal (Acetaldehyde)
b) Ethanoic anhydride (Acetic anhydride)
c) Ethyl propanoate
d) Propanamide
Question 4
Which molecule is an example of an acid chloride?
a) Propanoyl chloride
b) Ethanoic anhydride (Acetic anhydride)
c) Ethyl propanoate
d) Propanamide
Question 5
Which carbonyl compound would react violently with water?
a) Propan-2-one (acetone)
b) Ethanoyl chloride ( Acetyl chloride)
c) Ethanoic acid (Acetic acid)
d) Ethanal (Acetaldehyde)
Question 6
Conversion of an aldehyde to an alcohol is generally known as...
a) Reduction
b) Oxidation
c) Esterification
d) Polymerisation
Question 7
Conversion of a carboxylic acid to an ester is known as...
a) Reduction
b) Oxidation
c) Esterification
d) Polymerisation
Question 8
Why is sodium borohydride an important reagent in reducing a ketone?
a) It is good for hydrolysis type reactions
b) It is a good source of the hydride ion (H-)
c) It can act as a base
d) It can act as a free radical initiator.
Question 9
Why might an ester derivative of a drug be made?
a) To increase lipid solubility
b) To increase molecular weight
c) To improve compliance
d) To increase the melting point
Question 10
The products of the reaction of a carboxylic acid and an alcohol would be...
a) Ketone and water
b) Amide and water
c) Acid chloride and water
d) Ester and water
This set of Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Nomenclature and Structure of Carbonyl Groups – 1”.
1. Which of the following compounds do not contain a carbonyl group?
a) Alcohol
b) Aldehyde
c) Ketone
d) Carboxylic acid
View Answer
Answer: a
Explanation: Carbonyl groups are those which contain a carbon-oxygen double bond. In alcohols, the
bond between C and O is a single bond and hence does not contain a carbonyl group.
2. How many carbon atoms does formaldehyde have?
a) 0
b) 1
c) 2
d) 3
View Answer
Answer: b
Explanation: Formaldehyde is the common name of the simplest aldehyde, methanal. Its formula is HCHO and only one carbon which is also a part of the carbonyl group.
3. What is the common name of butanal?
a)
n-Butanaldehyde
b) α-Butanaldehyde
c) n-Butyraldehyde
d) α-Butyraldehyde
View Answer
Answer: c
Explanation: Butanal is a straight chain aldehyde with 4 carbon atoms including the carbonyl group. There is no substituent present in the carbon chain and hence the prefix n- is given in the common name.
4. What is the common name of the compound which has a CHO group attached to the sp2
hybridised carbon of a benzene ring?
a) Benzanal
b) Benzaldehyde
c) Benzenecarbaldehyde
d) Phthaldehyde
View Answer
Answer: b
Explanation: The IUPAC name of the simplest aromatic aldehyde carrying the CHO group on a benzene ring is benzenecarbaldehyde. Its common name is benzaldehyde, which is also accepted by IUPAC.
5. Which of the following is the incorrect name for the following
compound?
a) 3-Methylbutanal
b) β-Methylbutyraldehyde
c) γ-Methylbutyraldehyde
d) Isovaleraldehyde
View Answer
Answer: c
Explanation: The compound is a 4-carbon chain aldehyde with a methyl group substituted at the beta-carbon position, i.e., the carbon next to the carbon directly linked to the aldehyde group.
6. The prefix valer-
is used for generally used for naming aldehydes with how many carbon atoms in the structure?
a) 3
b) 4
c) 5
d) 6
View Answer
Answer: c
Explanation: When aldehydes have exactly 5 carbon atoms in their structure, including the carbonyl group and any substituted groups, the aldehyde is given the prefix valer- in the common naming system. For example, pentanal is named as n-Valeraldehyde.
7.
What is the correct IUPAC naming of the compound shown?
a) Benzenecarbaldehyde
b) Cyclohexanal
c) Cyclohexyl aldehyde
d) Cyclohexanecarbaldehyde
View Answer
Answer: d
Explanation: When the CHO group is attached to a ring, the suffix carbaldehyde is added after the name of the cycloalkane. The numbering of the ring carbons starts form the carbon attached to the aldehyde group.
8. Identify the correct IUPAC name of
CH3-CH=CH-CHO.
a) But-2-enal
b) 2-Butenal
c) Buten-2-al
d) Butenal
View Answer
Answer: a
Explanation: The carbon atom of the CHO group is assigned the first number. So, in this case, the double bond occurs at second carbon and hence, the prefix 2- is used for the naming of double bond -en.
9. The compound 3-Phenylprop-2-enal is also known as _________
a) Crotonaldehyde
b)
Cinnamaldehyde
c) Salicylaldehyde
d) Vanillin
View Answer
Answer: b
Explanation: In cinnamaldehyde, a benzene ring is attached to the end carbon of the aldehyde chain and also has a carbon double bond at the alpha carbon. Its formula is C6H5-CH=CH-CHO.
10. Identify the correct common name for the following compound.
a) 3-Methylcyclohexanecarbaldehyde
b) 3-Methylbenzecarbaldehyde
c) 3-Methylbenzaldehyde
d) γ-Methylcyclohexanecarbaldehyde
View Answer
Answer: d
Explanation: This compound is a cyclic aldehyde where numbering starts from the carbon to which the CHO group is attached. So, the carbon to which methyl group is attached is the third carbon. In the common system, this
carbon is known as the gamma carbon.
11. What is the IUPAC name of the sown compound?
a) Propane-1,2,3-trial
b) 3-Formylpentan-1,5-dial
c) 2-(Formylmethyl)butan-1,4-dial
d) Propane-1,2,3-tricarbaldehyde
View Answer
Answer: d
Explanation: There are three aldehydic groups present in the
given compound and none of them have preference over the other. The CHO groups are considered as substituents with the parent chain containing only three carbon atoms. This is done to give identical treatment to all the aldehydic groups.
12. How many aldehydic groups does the compound phthaldehyde have?
a) 1
b) 2
c) 3
d) 4
View Answer
Answer: b
Explanation: Phthaldehyde is an aromatic
compound containing two CHO groups, one on each adjacent carbon of the benzene ring. To give equal importance to both the aldehydic groups, it is named as benzene-1,2-dicarbaldehyde in the IUPAC system.
13. The compound 3-Bromobenzaldehyde is named as γ-Bromobenzaldehyde in the common system.
a) True
b) False
View Answer
Answer: b
Explanation: The prefix gamma- is used for substituents in a straight
carbon chain. For aromatic substituted compounds, the prefixes ortho-, meta- and para- are used. Hence, 3-Bromobenzaldehyde is named as m-Bromobenzaldehyde in the common system.
14. Vanillin is an aldehydic compound.
a) True
b) False
View Answer
Answer: a
Explanation: Vanillin consists of a benzene ring substituted with CHO group and OH group on opposite side. Additionally, there is a methoxy group
at meta position with respect to the aldehydic group. Its IUPAC name is 4-Hydroxy-3-methoxybenzaldehyde.
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