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Aldehyde and ketones are organic compounds, in which the functional group is the carbonyl group. Aldehyde and ketones along with other functional groups are used for industrial purposes.
In aldehyde, the carbonyl group has one hydrogen atom attached to it together with a second hydrogen atom or a hydrogen group (of the alkyl group or containing benzene ring). The aldehydes (acidic and aliphatic) are primarily named after their longest carbon chain. A suffix “carbaldehyde” is used, in a ring form of aldehyde.
In ketones, the carbonyl group has 2 hydrocarbon groups. Either the one containing benzene rings or alkyl groups. Ketone does not have a hydrogen atom attached to the carbonyl group. The parent alkane name is considered while naming a ketone. The “Anone” suffix is attached. The position of the carbonyl group is denoted by a particular number while giving a name to the ketone. The alkyl group attached to carbonyl is also included in the nomenclature.
Ques 1. What is the product in the reaction of benzaldehyde and formaldehyde in presence of an aqueous NaOH solution?
- Benzyl alcohol + sodium formate
- Sodium benzoate + methanol
- Benzyl alcohol + methanol
- Sodium benzoate + sodium formate
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Answer: (a) It is a crossed Cannizzaro's reaction.
Explanation: 
Ques 2. Which of the following has the most acidic hydrogen?
- Hexane-2,4-dione
- Hexane-2,3-dione
- Hexane-2,5-dione
- Hexane-3-one
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Answer: (a)
Explanation: The acidic strength of a compound is directly proportional to the electron-withdrawing capacity of the group. Hexane 2,4-dione has the most acidic hydrogen, as the carbanion left after the removal of H+ is in resonance.
Hexane-2,4-dione Hexane-2,3-dione
Hexane-2,5-dione Hexane-3-one
Ques 3. A new C-C bond formation is possible in
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Answer: (b,d)
Explanation: In Cannizzaro Reaction, no new C-C bond is formed.
2HCHO —→ COO- + MeOH
In Friedel craft's reaction, a new C-C bond is formed.
In Clemmensen reduction, no new C-C bond is formed.
In Reimer tiemann reaction, a new C-C bond is formed.
Ques 4. Under Wolff-Kishner reduction conditions, what are the possible conversions?
- Cyclohexanone into cyclohexane
- Benzaldehyde into benzyl alcohol
- Cyclohexanone into cyclohexanol
- Benzophenone into diphenylmethane
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Answer: (a,d)
Explanation: Under Wolff Kishner reduction, an aldehyde or ketone is converted into a corresponding alkane.
Ques 5. The formation of cyanohydrin from a ketone is an example of which of the following?
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Answer: (b)
Explanation: A nucleophilic addition reaction is a chemical addition reaction in which a nucleophile forms a sigma bond with an electron-deficient species.
Ques 6. Benzoic acid reacts with conc.HNO3 and conc.H2SO4 to give
- o-nitrobenzoic acid
- p-nitrobenzoic acid
- m-nitrobenzoic acid
- o,p-dinitrobenzoic acid
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Answer: (c).
Explanation: When benzoic acid reacts with conc.HNO3 and conc.H2SO4, m-nitrobenzoic acid is formed.
- The H atom of benzoic acid is replaced by the nitro group.
- The -COOH group is meta-directing in nature, as it is the electron-withdrawing group. It pulls the electron density towards itself and act as a deviating group on the benzoic acid.
Ques 7. Which inorganic compound produces an organic compound on heating?
- Ammonium cyanate
- Soda lime
- Sodamide
- Potassium cyanide
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Answer: (a)
Explanation: Ammonium cyanate on heating gives urea (organic compound).
NH4+CNO- â NH2CONH2
(Ammonium Cyanide) (Urea)
Sodamide (NaNH2): It is used as a strong base in liquid ammonia solution. It is the reagent of choice for drying ammonia (liquid/gas). Mainly functions as a nucleophile.
Potassium Cyanide (KCN): It is a toxic inorganic substance. It is formed by th erection of HCN with KOH.
Ques 8. The reaction of ethyl formate with an excess of CH3MgI followed by hydrolysis gives
- Ethanol
- n-propyl alcohol
- Propanal
- Isopropyl alcohol
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Answer: (d) The reaction can be shown as under:
Explanation: 
Ques 9. Formic acid and acetic acid are distinguished by reaction with
- Sodium ethoxide
- Sodium
- HgCl2
- 2,4-dinitrophenylhydrazine
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Answer: Correct answe is c.
Explanation: 2,4-dinitrophenylhydrazine is also called Brady’s reagent. It reacts with carbonyl compounds (aldehydes and ketone) to give a coloured precipitate. These sediments have a sharp melting point. The melting points of the precipitates confirm the carbonyl compounds.
Formic acid has an aldehyde group so it reacts with the reagent and forms a yellow-coloured precipitate of 2,4-dinitro phenyl hydrazone. However, acetic acid does not create any such precipitate.
Ques 10. Heating a mixture of sodium benzoate and soda lime gives
- Calcium benzoate
- Benzene
- Sodium benzoate
- Methane
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Answer: (b)
Explanation: 
Ques 11. When benzene is oxidized by V2O5 in presence of air, it produces
- Benzoic acid
- Maleic anhydride
- Benzoic anhydride
- Benzaldehyde
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Answer: (b)
Explanation: 
Ques 12. Clemmensen reduction takes place in the presence of
- Zn-Hg with HCl
- Glycol with KOH
- H2 and Pt as catalysts
- LiAlH4
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Answer: (b)
Explanation: Clemenson reduction is carried out in presence of Zn-Hg with HCl. This reaction converts the carbonyl group into a methylene group. It is suitable for compounds sensitive to alkalis.
Ques 13. Which of the following tests can distinguish between acetaldehyde and phenylacetaldehyde?
- Iodoform test.
- Benedict’s test.
- Fehling’s solution test.
- Tollen’s reagent test.
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Answer: (a)
Explanation: When Iodine and sodium hydroxide are added to a compound that contains either a methyl ketone or a secondary alcohol with a methyl group in the alpha position, a pale yellow precipitate of iodoform or triiodomethane is formed. It can be used to identify aldehydes or ketones.
Ques 14. Find the correct reactivity order for the following with phenyl magnesium bromide (PhMgBr).
I – Acetaldehyde, II – Acetone, III – Benzophenone
- II > I > III.
- III > II > I.
- I > II > III.
- I > III > II.
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Answer: (a)
Explanation: Aldehyde is more reactive than ketone for nucleophilic addition reaction. The electrophilicity of carbonyl carbon is influenced by the electron donating group attached and steric crowding.
Ques 15. The strong base can abstract alpha hydrogen from which of the following?
- Alkane
- Ketone
- Amine
- Alkene
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Answer: (b).
Explanation: Ketones are stronger acids than alkenes and alkanes as in the conjugated base, negative charge resides on the more electronegative carbon atom.
Ques 16. Which of the following will give a corresponding aldehyde or ketone on oxidation?
- ortho-Nitrophenol.
- 2-Hydroxypropane.
- 2-Methyl-2-hydroxy propane.
- Phenol
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Answer: (b).
Explanation: The primary or secondary alcohol can be oxidized to the corresponding aldehyde, ketone, or carboxylic acid by oxidation.
2-Hydroxypropane in the presence of Ag dust at 250 degrees celsius in presence of air form the respective carbonyl compound.
Ques 17. Which of the following will most readily undergo a nucleophilic addition reaction?
- CH3CH2CH2COCH3.
- CH3CHO.
- CH3CH2CHO.
- CH3COCH3.
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Answer. (b) CH3CHO.
Explanation: The electron density at the carbonyl carbon increases with the increase in the +I effect.
As a result, the chances of attack by a nucleophile decrease. The increasing order of the reactivity is:
CH3CH2CH2COCH3<CH3CH2CHO<CH3COCH3< CH3CHO
Ques 18. On reduction of a carbonyl compound by Zn-Hg and Conc. HCl, it is converted to an alkane. This reaction is known as,
- Dow reduction.
- Cope reduction.
- Clemmensen reduction.
- Wolf-Kishner reduction.
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Answer: Option c
Explanation: Clemmensen reduction: The reduction of aldehydes and ketones to an alkane using zinc amalgam and hydrochloric acid.
Ques 19. Which among the following is formed when benzoyl chloride is hydrogenated over a catalyst, palladium on barium sulphate?
- C6H5OH
- C6H5CHO
- C6H5Cl
- C6H5COCH3
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Answer: (b)
Explanation: The hydrogenation of benzyl chloride in the presence of Palladium or Barium Sulphate gives Benzaldehyde.
Ques 20. What is the angle between the carbonyl C-O bond and the bond between the carbonyl carbon and the atom connected to it?
- 60 degrees.
- 90 degrees.
- 120 degrees.
- 135 degrees.
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Answer: c.
Explanation: The carbonyl carbon and the 3 atoms attached to it in the same plane and the pie electron cloud is above and below this plane. The bond angle is approximately 120 degrees as expected of a trigonal planar structure.
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