Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids

Bihar Board 12th Chemistry Objective Questions and Answers

Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids

Question 1.
Which of the following structures is not correctly matched ?
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 1
Answer:
(c)

Question 2.
Which of the following carbonyl compounds is most polar ?
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 2
Answer:
(d)

Question 3.
Ketones
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 3can be obtained in one step by (where R and R’ are alkyl groups)
(a) hydrolysis of esters
(b) oxidation of primary alcohols
(c) oxidation of secondary alcohols
(d) reaction of alkyl halides with alcohols
Answer:
(c) oxidation of secondary alcohols

Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids

Question 4.
Ozonolysis of an organic compound gives formaldehyde as one of the products. This confirms the presence of
(a) two ethylenic double bonds
(b) a vinyl group
(c) an isopropyl group
(d) an acetylenic triple bond
Answer:
(b) a vinyl group

Question 5.
In the following reaction, product (P) is
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 4
(a) RCHO
(b) RCH
(c) RCOOH
(d) RCH2OH
Answer:
(a) RCHO

Question 6.
Benzoyl chloride on reduction with H2/Pd-BaSO4 produces
(a) benzoic acid
(b) benzyl alcohol
(c) benzoyl sulphate
(d) benzaldehyde
Answer:
(d) benzaldehyde

Question 7.
The oxidation of toluene to benzaldehyde by chromyl chloride is called
(a) Etard reaction
(b) Riemer-Tiemann reaction
(c) Wurtz reaction
(d) Cannizzaro’s reaction
Answer:
(a) Etard reaction

Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids

Question 8.
There is a large difference in the boiling points of butanal and butan-l-ol due to
(a) intermolecular hydrogen bonding in butan-l-ol
(b) intramolecular hydrogen bonding in butanal
(c) higher molecular mass of butan-l-ol
(d) resonance shown by butanal
Answer:
(a) intermolecular hydrogen bonding in butan-l-ol

Question 9.
Arrange the following compounds in increasing order of their reactivity in nucleophilic addition reactions. Ethanal, Propanal, Propanone, Butanone
(a) Butanone < Propanone < Propanal < Ethanal
(b) Propanone < Butanone < Ethanal < Propanal
(c) Propanal < Ethanal < Propanone < Butanone
(d) Ethanal < Propanal < Propanone < Butanone
Answer:
(a) Butanone < Propanone < Propanal < Ethanal

Question 10.
Which among the following is most reactive to give nucleophilic addition ?
(a) FCH2CHO
(b) CICH2CHO
(c) BrCH2CHO
(d) ICH2CHO
Answer:
(a) FCH2CHO

Question 11.
The addition of HCN to carbonyl compounds is an example of
(a) nucleophilic addtion
(b) electrophilic addtion
(c) free readical addition
(d) electromeric addtion
Answer:
(a) nucleophilic addtion

Question 12.
Which of the following compounds does not react with NaHS03 ?
(a) HCHO
(b) C6H5COCH3
(c) CH3COCH3
(d) CH3CHO
Answer:
(b) C6H5COCH3

Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids

Question 13.
Aldehydes other than formaldehyde react with Grignard’s reagent to give addition products which on hydrolysis give
(a) tertiary alcohols
(b) secondary alcohols
(c) primary alcohols
(d) carboxylic acids
Answer:
(b) secondary alcohols

Question 14.
Identify reactant (X) in the given reaction sequence.
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 5
(a) CH3MgCl
(b) CH3COCl + Mg
(c) MgCl2
(d) CH3CH2MgCI
Answer:
(a) CH3MgCl

Question 15.
The best method to purify impure acetone is
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 6
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 7
Answer:
(b)

Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids

Question 16.
What is the test to differentiate between pentan-2-one and pentan-3-one ?
(a) Iodoform test
(b) Benedict’s test
(c) Fehling’s test
(d) Aldol condensation
Answer:
(a) Iodoform test

Question 17.
The best oxidising agent for oxidation of
CH , — CH = CH — CHO to CH3 — CH = CH — COOH is
(a) Baeyer’s reagent
(b) Tollen’s reagent
(c) Schiff s reagent
(d) acidified dichromate
Answer:
(b) Tollen’s reagent

Question 18.
In the following sequence of reaction, the final product (Z) is
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 8
(a) ethanal
(b) propan-2-ol
(c) propanone
(d) propan-l-ol
Answer:
(c) propanone

Question 19.
Which of the following does not answer iodoform test ?
(a) n-Butyl alcohol
(b) sec-Butyl alcohol
(c) Acetophenone
(d) Acetaldehyde
Answer:
(a) n-Butyl alcohol

Question 20.
To differentiate between pentan-2-one and pentan-3-one a test is carried out. Which of the following is the correct answer ?
(a) Pentan-2-one will give silver mirror test
(b) Pentan-2-one will give iodoform test
(c) Pentan-3-one will give iodoform test
(d) None of these
Answer:
(b) Pentan-2-one will give iodoform test

Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids

Question 21.
Which of the following compounds will give a coloured crystalline compound with
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 9
(a) CH3COCl
(b) CH3COOC2H5
(c) CH3COCH3
(d) CH3CONH2
Answer:
(c) CH3COCH3

Question 22.
Which of the following will not give aldol condensation ?
(a) Phenyl acetaldehyde
(b) 2-Methylpentanal
(c) Benzaldehyde
(d) I-Phenylpropanone
Answer:
(c) Benzaldehyde

Question 23.
Propanal on treatment with dilute sodium hydroxide gives
(a) CH3CH2CH2CH2CH2CHO
(b) CH3CH2CH(OH)CH2CH2CHO
(c) CH3CH2CH(OH)CH(CH3)CHO
(d) CH3CH2COOH
Answer:
(c) CH3CH2CH(OH)CH(CH3)CHO

Question 24.
The final product (Y) in the following sequence of 300°C
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 10
(a) an alkene
(b) a carboxylic acid
(c) an aldehyde
(d) sodium salt of carboxylic acid
Answer:
(d) sodium salt of carboxylic acid

Question 25.
Which of the following is the most reactive isomer ?
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 11
Answer:
(a)

Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids

Question 26.
When propanal reacts with 2-methylpropanal in presence of NaOH, four different products are formed. The reaction is known as
(a) aldol condensation
(b) cross aldol condensation
(c) Cannizzaro reaction
(d) HVZ condensation
Answer:
(b) cross aldol condensation

Question 27.
Which compound is obtained when acetaldehyde is treated with dilute solution of caustic soda ?
(a) Sodium acetate
(b) Resinous mass
(c) Aldol
(d) Ethyl acetate
Answer:
(c) Aldol

Question 28.
Which of the following compound will undergo self aldol condensation in the presence of cold dilute alkali ?
(a) CH ≡ C – CHO
(b) CH2 = CHCHO
(c) C6H5CHO
(d) CH3CH,CHO
Answer:
(d) CH3CH,CHO

Question 29.
Which of the following compounds will undergo Cannizzaro reaction ?
(a) CH3CHO
(b)CH3COCH3
(c) C6H5CHO
(d) C6H5CH2CHO
Answer:
(c) C6HsCHO

Question 30.
Which of the following does not undergo Cannizao’s recations ?
(a) Benzaldehyde
(b) 2-Methylpropanal
(c) p-Methoxybenzaldehyde
(d) 2,2-Dimethylpropanal
Answer:
(b) 2-Methylpropanal

Question 31.
Which of the following aldehydes will show Cannizzaro reaction ?
(a)HCHO
(b)C6H5CHO
(c) (CH3)3CCHO
(d) All of these
Answer:
(d) All of these

Question 32.
What are the correct steps to convert acetaldehyde to acetone ?
(a) CH3MgBr, H2O, Oxidation
(b) Oxidation, Ca(OH)2, Heat
(c) Reduction, KCN, Hydrolysis
(d) Oxidation, C2H5ONa, Heat
Answer:
(b) Oxidation, Ca(OH)2, Heat

Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids

Question 33.
The correct structure representation of carboxylate ion is
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 12
Answer:
(b)

Question 34.
Which of the following will not yield acetic acid on strong oxidation ?
(a) Butanone
(b) Propanone
(c) Ethyl ethanoate
(d) Ethanol
Answer:
(c) Ethyl ethanoate

Question 35.
Various products formed on oxidation of 2,5- dimethylhexan-3-one are
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 13
(c) CH3COOH
(d) HCOOH
Answer:
(c) CH3COOH

Question 36.
a-Hydroxypropanoic acid can be prepared from ethanal by following the steps given in the sequence.
(a) Treat with HCN followed by acidic hydrolysis
(b) Treat with NaHSO3 followed by reaction with Na-,CO3
(c) Treat with H2SO4 followed by hydrolysis
(d) Treat with K-,Cr2O7 in presence of sulphuric acid
Answer:
(a) Treat with HCN followed by acidic hydrolysis

Question 37.
Carboxylic acids dimerise due to
(a) high molecular weight
(b) coordinate bonding
(c) intermolecular hydrogen bonding
(d) covalent bonding
Answer:
(c) intermolecular hydrogen bonding

Question 38.
Which of the following earboxylic acids is highly insoluble in water ?
(a) Propanoic acid
(b) Butanoic acid
(c) Pentanoic acid
(d) Decanoic acid
Answer:
(d) Decanoic acid

Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids

Question 39.
Which of the following compounds would have the smallest value for pKa ?
(a) CHF2CH2CH2COOH
(b) CH3CH2CF2COOH
(c) CH2FCFCH2COOH
(d) CH3CF2CH2COOH
Answer:
(b) CH3CH2CF2COOH

Question 40.
Which of the following is the correct order of relative strength of acids ?
(a) ClCH2COOH > BiCH2COOH > FCH2COOH
(b) BrCH2COOH > ClCH2COOH > FCH2COOH
(c) FCH2COOH > ClCH2COOH > BrCH2COOH
(d) ClCH2COOH > FCH2COOH > BrCH2COOH
Answer:
(c) FCH2COOH > ClCH2COOH > BrCH2COOH

Question 41.
In a set of the given reactions, acetic acid yielded a product C.
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 14
Product C would be
(a) CH3CH(OH) C2H5
(b) CH3COC6H5
(c) CH3CH(OH)C6H5
(d)
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 15
Answer:
(d)

Question 42.
What happens when a carboxylic acid is treated with lithium aluminium hydride ?
(a) Aldehyde is formed
(b) Primary alcohol is formed
(c) Ketone is formed
(d) Grignard reagent is formed
Answer:
(b) Primary alcohol is formed

Question 43.
Which of the following will not undergo HVZ reaction ?
(a) Propanoic acid
(b) Ethanoic acid
(c) 2-Methylpropanoic acid
(d) 2, 2-Dimethylpropanoic acid
Answer:
(d) 2, 2-Dimethylpropanoic acid

Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids

Question 44.
Which of the following statements is correct regarding formic acid ?
(a) It is a reducing agent
(b) It is a weaker acid than acetic acid
(c) It is an oxidising agent
(d) When its calcium salt is heated, it forms acetone
Answer:
(a) It is a reducing agent

Question 45.
The final product (c) obtained in the reaction sequence is
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 16
Answer:
(c)

Question 46.
Which of the following compounds is most reactive towards nucleophilic addition reactions ?

Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 17
Answer:
(b)

Question 47.
The correct order of increasing acidic strength is…..
(a) phenol < ethanol < chloroacetic acid < acetic acid
(b) ethanol < phenol < chloroacetic acid < acetic acid
(c) ethanol < phenol < acetic acid < chloroacetic acid
(d) chloroacetic acid < acetic acid < phenol < ethanol
Answer:
(c) ethanol < phenol < acetic acid < chloroacetic acid

Question 48.
The reagent which does not react with both, acetone and benzaldehyde is……..
(a) sodium hydrogensulphite
(b) phenyl hydrazine
(c) Fehling’s solution
(d) Grignard reagent
Answer:
(c) Fehling’s solution

Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids

Question 49.
Cannizzaro’s reaction is not given by
Bihar Board 12th Chemistry Objective Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids 18
(c) HCHO
(d) CH3CHO
Answer:
(d) CH3CHO

Question 50.
Which of the following compounds will give butanone on oxidation with alkaline KMnO4 solution ?
(a) Butan-l-ol
(b) Butan-2-ol
(c) Both of these
(d) None of these
Answer:
(b) Butan-2-ol

Question 51.
In Clemmensen reduction carbonyl compound is treated with……….
(a) zinc amalgam + HCl
(b) sodium amalgam + HCl
(c) zinc amalgam + nitric acid
(d) sodium amalgam + HNO3
Answer:
(a) zinc amalgam + HCl

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