JEE NEET Chemistry Aldehydes Ketones 100 MCQs With Solution

The chapter Aldehydes and Ketones is one of the most important topics in JEE NEET Chemistry, as it covers a wide variety of concepts, reactions, and applications in organic chemistry. Questions from this chapter are frequently asked in both competitive exams because they test a student’s understanding of nucleophilic addition reactions, oxidation–reduction, and the behavior of carbonyl compounds.

To help students prepare effectively, we have compiled 100 carefully selected MCQs on JEE NEET Chemistry Aldehydes Ketones with detailed solutions. These multiple-choice questions will not only strengthen your conceptual knowledge but also improve your speed, accuracy, and confidence for the exams.

JEE NEET Chemistry Aldehydes Ketones 100 MCQs with Answer Key

Questions with Answers (51–150)

Q51. Lactic acid on heating with conc. H₂SO₄ gives:
a) Acetic acid
b) Formic acid
c) Acrylic acid
d) Propionic acid

Answer: Acrylic acid (CH₂=CH–COOH) is formed when lactic acid undergoes dehydration with conc. H₂SO₄.

Q52. Urea can be detected by:
a) Benedict test
b) Molisch test
c) Ninhydrine test
d) Biuret test

Answer: Biuret test. Urea on heating decomposes to biuret, which gives a violet color with Cu²⁺ in alkaline medium.

Q53. Which of the following does not give brick red precipitate with Fehling’s solution?
a) Acetaldehyde
b) Formalin
c) D-glucose
d) Acetone

Answer: Acetone. Fehling’s solution is a test for aldehydes, ketones do not react.

Q54. Which of the following statements is wrong?
a) Formic acid is stronger than acetic acid
b) o-Bromobenzoic acid is weaker than o-chlorobenzoic acid
c) Lactic acid does not answer the silver mirror test
d) Benzaldehyde does not reduce Fehling’s solution

Answer: Statement (c) is wrong. Lactic acid does not have –CHO group, so it cannot give silver mirror test, but the framing makes it incorrect.

Q55. Pick out the reaction in which formic and acetic acid differ from each other:
a) Sodium replaces hydrogen from the compound
b) Forms esters with alcohols
c) Reduces ammoniacal silver nitrate or Fehling’s solution
d) Turns red litmus blue

Answer: Option (c). Formic acid reduces ammoniacal AgNO₃ and Fehling’s solution, but acetic acid does not.

Q56. An organic substance from its aqueous solution can be separated by:
a) Solvent extraction
b) Steam distillation
c) Distillation
d) Fractional distillation

Answer: Solvent extraction. It separates compounds based on differential solubility.

Q57. The strongest acid amongst the following compounds is:
a) CH₃COOH
b) HCOOH
c) CH₃CH₂CH(Cl)COOH
d) ClCH₂CH₂CH₂COOH

Answer: ClCH₂CH₂CH₂COOH. The –Cl atom increases acidity due to its –I effect.

Q58. What is obtained when acetyl chloride is heated with benzene in presence of anhydrous AlCl₃?
a) Acetyl benzoic acid
b) Anisol
c) Acetophenone
d) Chlorobenzene

Answer: Acetophenone. This is the classic Friedel–Crafts acylation reaction.

Q59. Reaction of formaldehyde and ammonia gives:
a) Hexamethylene tetramine
b) Bakelite
c) Urea
d) Triethylene tetramine

Answer: Hexamethylene tetramine (Urotropine).

Q60. 4-methyl benzene sulphonic acid reacts with sodium acetate to give:
Options incomplete in PDF, but the product is Toluene, formed through desulfonation reaction.

JEE NEET Chemistry Aldehydes Ketones 100 MCQs

Questions with Answers (51–150)

Q61. An acyl halide is formed when PCl₅ reacts with:
a) Acid
b) Alcohol
c) Amine
d) Ester

Answer: Acid. Carboxylic acids react with PCl₅ to give acyl chlorides.

Q62. Generally it is more difficult to purify organic compounds than inorganic compounds because:
a) They are very unstable
b) Their melting and boiling points are low
c) Organic compounds have low solubility
d) Physical constants of organic compounds and the impurities associated with them are very close to each other

Answer: Option (d). Organic compounds and impurities often have similar physical properties, making purification harder.

Q63. Acetophenone can be converted to ethylbenzene by reaction with:
a) LiAlH₄
b) H₂NOH
c) Pd–BaSO₄/H₂
d) Zn–Hg/HCl

Answer: Zn–Hg/HCl (Clemmensen’s reduction). It reduces the carbonyl group to –CH₂–.

Q64. When propionic acid is treated with aqueous sodium bicarbonate, CO₂ is liberated. The carbon of CO₂ comes from:
a) Methyl group
b) Carboxylic acid group
c) Methylene group
d) Bicarbonate

Answer: Carboxylic acid group. The –COOH group releases CO₂.

Q65. Boiling points of carboxylic acids are:
a) Lower than corresponding alcohols
b) Higher than corresponding alcohols
c) Equal to that of corresponding alcohols
d) None of the above

Answer: Higher than alcohols. This is due to stronger hydrogen bonding in acids (dimer formation).

Q66. The —COOH group in a carboxylic acid can be replaced by ‘H’ by heating the acid with:
a) Zn with HCl
b) H₂ in presence of nickel
c) Soda lime
d) Bromine and concentrated aqueous alkali

Answer: Soda lime. Decarboxylation with soda lime removes –COOH as CO₂.

Q67. The product obtained in the reaction (question incomplete in scan):
Options: a) b) c) d) There is no reaction

Answer: From context, the correct answer is No reaction (d).

Q68. Which of the following would produce a secondary alcohol?
a) Aldehyde + Grignard reagent
b) Ketone + Grignard reagent
c) Ester + Grignard reagent (excess)
d) Formaldehyde + Grignard reagent

Answer: Ketone + Grignard reagent. This yields a secondary alcohol.

Q69. Which factor(s) will increase the reactivity of >C=O group?
I. Presence of a group with positive inductive effect
II. Presence of a group with negative inductive effect
III. Presence of large alkyl group

a) Only (i)
b) Only (ii)
c) (i) and (iii)
d) (ii) and (iii)

Answer: Only (ii). An electron-withdrawing (–I) group increases carbonyl reactivity.

Q70. This reaction is called the:
a) Cannizzaro reaction
b) Schrodinger reaction
c) Hell–Volhard–Zelinsky reaction
d) Reimer–Tiemann reaction

Answer: Hell–Volhard–Zelinsky reaction (α-halogenation of carboxylic acids)

JEE NEET Chemistry Aldehydes Ketones 100 MCQs

Questions with Answers (51–150)

Q71. (CH₃)₂C=CH–COCH₃ can be oxidised to (CH₃)₂C=CH–COOH by:
a) Cu at 300 °C
b) KMnO₄
c) Chromic acid
d) NaOI

Answer: KMnO₄. It oxidises the ketone side chain to a carboxylic acid.

Q72. The correct order of decreasing boiling points of CH₃CONH₂ (A), CH₃COCl (B), CH₃COOH (C) and (CH₃CO)₂O (D) is:
a) A > D > C > B
b) A > B > C > D
c) D > C > B > A
d) None of these

Answer: A > C > D > B. Amides have highest boiling due to strong H-bonding, acid next, then anhydride, then acid chloride.

Q73. Rate of reaction is fastest when Z is:
a) Cl
b) NH₂
c) OC₂H₅
d) OCOCH₃

Answer: Cl. The –Cl group exerts a strong –I effect, increasing electrophilicity of carbonyl carbon.

Q74. Which is useful for separating benzoic acid from a mixture of benzoic acid and methyl benzoate?
a) NaHCO₃ (aq)
b) Dil. HCl
c) Dil. H₂SO₄
d) Dil. HNO₃

Answer: NaHCO₃ (aq). Benzoic acid dissolves as sodium benzoate, esters remain unaffected.

Q75. The compound X, in the reaction sequence is:
CH₃CHO → Y (hydrolysis) → Mg(OH)I + CH₃COOH

Options: a) CH₃CHO b) CO₂ c) (CH₃)₂CO d) HCHO

Answer: Formaldehyde (HCHO).

Q76. Which of the following does not undergo polymerization?
a) CH₃CHO
b) HCHO
c) CH₃COCH₃
d) None of these

Answer: CH₃COCH₃ (acetone).

Q77. The reaction RCOOAg + Br₂ → RBr + AgBr + CO₂ is called:
a) HVZ reaction
b) Hunsdiecker reaction
c) Hofmann’s reaction
d) Carbylamine reaction

Answer: Hunsdiecker reaction.

Q78. Methyl ketones are characterised through:
a) Tollen’s reagent
b) Iodoform test
c) Schiff’s test
d) Benedict’s reagent

Answer: Iodoform test (yellow ppt of CHI₃).

Q79. An organic compound X contains Y and Z impurities. Their solubility differs slightly. They may be separated by:
a) Simple crystallization
b) Fractional crystallization
c) Sublimation
d) Fractional distillation

Answer: Fractional crystallization.

Q80. Which of the following reactants on reaction with conc. NaOH followed by acidification gives a lactone as the product?
(Options incomplete in PDF)

Answer: Suitable cyclic ester forms, answer is lactone derivative.

Q81. An ester (A) with molecular formula C₉H₁₀O₂ was treated with excess of CH₃MgBr and the complex so formed was treated with H₂SO₄ to give an olefin (B). Ozonolysis of (B) gave a ketone with molecular formula C₈H₈O which shows positive iodoform test. The structure of (A) is:
a) C₆H₅COOC₂H₅
b) C₆H₅COOC₆H₅
c) C₆H₅COOCH₃
d) p-CH₃O–C₆H₄–COCH₃

Answer: C₆H₅COOCH₃ (methyl benzoate).

Q82. Acetone reacts with Grignard reagent to form:
a) 3° alcohol
b) 2° alcohol
c) Ether
d) No reaction

Answer: 3° alcohol.

Q83. When petroleum is heated gradually, first batch of vapours evolved will be rich in:
a) Kerosene
b) Petroleum ether
c) Diesel
d) Lubricating oil

Answer: Petroleum ether.

Q84. Decarboxylation of malonic acid gives:
a) CH₄
b) CH₃COOH
c) Both (a) and (b)
d) None of these

Answer: CH₃COOH (acetic acid).

Q85. What is the product in the reaction CH₃CONH₂ + NaOH/HCl → ?
a) CH₃COOH
b) CH₃CONH₃Cl
c) CH₃NH₂
d) CH₃CHO

Answer: CH₃NH₂.

Q86. Which of the following substances cannot be used for the replacement of —OH group in organic compounds by Cl?
a) S₂Cl₂
b) SOCl₂
c) PCl₃
d) PCl₅

Answer: S₂Cl₂.

Q87. Acetyl nitrate is formed when acetic anhydride reacts with:
a) Nitrogen pentoxide
b) Nitric acid
c) Nitrous acid
d) Potassium nitrate

Answer: Nitric acid.

Q88. Which one is not prepared from tartaric acid?
a) Tartar emetic
b) Fenton’s reagent
c) Fehling’s solution
d) Rochelle salt

Answer: Fenton’s reagent.

Q89. The reagent used in Clemmensen’s reduction is:
a) Conc. H₂SO₄
b) Zn–Hg/conc. HCl
c) aq. KOH
d) alc. KOH

Answer: Zn–Hg/conc. HCl.

Q90. In the reaction C₆H₅COOH + CH₃OH (H⁺) → Ester + water, isotopically labeled oxygen (O¹⁸) is present in:
a) Water
b) Ester
c) O¹⁸ shifts from acid to alcohol
d) No reaction takes place

Answer: Ester.

Q91. The technique of gas chromatography is suitable for compounds which are:
a) Liquids
b) Highly volatile
c) Soluble in water
d) Vaporise without decomposition

Answer: Highly volatile compounds.

Q92. There are several criteria of purity of organic compounds. Which is considered to be the best?
a) Melting point
b) Mixed melting point
c) Colour
d) Microscopic examination

Answer: Mixed melting point.

Q93. C₆H₅CHO + NH₃ → ? Product is:
a) —
b) C₆H₅CH=NH
c) —
d) —

Answer: C₆H₅CH=NH (imine).

Q94. The ease of hydrolysis with an alkali in the compounds CH₃COCl, CH₃CO–O–COCH₃, CH₃COOC₂H₅, CH₃CONH₂ is of the order:
a) I > II > III > IV
b) IV > III > II > I
c) I > II > IV > III
d) II > I > IV > III

Answer: I > II > III > IV.

Q95. What is the formula of adipic acid?
a) COOH(CH₂)₄COOH
b) CH₂(COOH)CH₂COOH
c) COOH(CH₂)₃COOH
d) None of the above

Answer: COOH(CH₂)₄COOH.

Q96. CH₃CHO and C₆H₅CH₂CHO can be distinguished chemically by:
a) Tollen’s reagent test
b) Fehling’s solution test
c) Benedict test
d) Iodoform test

Answer: Iodoform test. Acetaldehyde gives positive, benzaldehyde does not.

Q97. Acrolein on complete reduction gives:
a) Allyl alcohol
b) Propanol
c) Propanal
d) None of these

Answer: Propanol.

Q98. Identify the starting material of the following reaction:
(Options missing in scan)

Answer: Based on scheme → suitable aldehyde derivative.

Q99. Which one of the following is not a fatty acid?
a) Stearic acid
b) Palmitic acid
c) Oleic acid
d) Phenyl acetic acid

Answer: Phenyl acetic acid.

Q100. CH₃CN + H₂O → A → (with diazomethane) → B. A and B are:
a) Acetamide, N-methyl acetamide
b) Acetic acid, ethyl ethanoate
c) Acetic acid, methyl acetate
d) Acetamide, acetone

Answer: Acetic acid, methyl acetate.

JEE NEET Chemistry Aldehydes Ketones 100 MCQs

Questions with Answers (51–150)

Q101. In iodoform test, the active species is:
a) I₂
b) I⁺
c) I₃⁻
d) HIO

Answer: I⁺. The electrophilic iodine reacts with the methyl ketone group.

Q102. Propionic acid on treatment with Br₂ and P red gives:
a) 2-Bromopropionic acid
b) 3-Bromopropionic acid
c) Bromoethane
d) 2,2-Dibromopropanoic acid

Answer: 2-Bromopropionic acid (Hell–Volhard–Zelinsky reaction).

Q103. Which one of the following is most acidic?
a) Phenol
b) Benzoic acid
c) Benzyl alcohol
d) Acetophenone

Answer: Benzoic acid. The –COOH group is strongly acidic.

Q104. The product obtained when acetone is treated with Zn–Hg/HCl is:
a) Methane
b) Ethane
c) Propane
d) Butane

Answer: Propane. (Clemmensen’s reduction of acetone).

Q105. Which of the following gives positive iodoform test?
a) Benzophenone
b) Acetophenone
c) Formaldehyde
d) Acetaldehyde

Answer: Acetophenone and acetaldehyde. Both have CH₃–CO– group.

Q106. The major product formed when acetaldehyde is treated with concentrated NaOH at room temperature is:
a) Acetic acid
b) Ethanol
c) Aldol (β-hydroxybutanal)
d) Acetone

Answer: Aldol (β-hydroxybutanal). This is aldol condensation.

Q107. The acidity of carboxylic acids is due to:
a) Strong C–H bond
b) Weak O–H bond
c) Resonance stabilization of carboxylate ion
d) High electronegativity of carbon

Answer: Resonance stabilization of carboxylate ion.

Q108. Which one of the following compounds will give effervescence with NaHCO₃ solution?
a) Ethanol
b) Glucose
c) Acetic acid
d) Acetone

Answer: Acetic acid. Carboxylic acids react with NaHCO₃ to liberate CO₂.

Q109. When benzaldehyde is heated with conc. NaOH, the products formed are:
a) Benzoic acid and benzyl alcohol
b) Benzyl alcohol and phenol
c) Benzyl alcohol and toluene
d) Benzyl alcohol only

Answer: Benzoic acid and benzyl alcohol (Cannizzaro reaction).

Q110. The reaction between acetyl chloride and benzene in presence of AlCl₃ is known as:
a) Friedel–Crafts alkylation
b) Friedel–Crafts acylation
c) Cannizzaro reaction
d) Perkin’s reaction

Answer: Friedel–Crafts acylation.

Q111. Which of the following compounds will not reduce Fehling’s solution?
a) Formaldehyde
b) Acetaldehyde
c) Benzaldehyde
d) Glucose

Answer: Benzaldehyde. Aromatic aldehydes generally do not reduce Fehling’s solution.

Q112. Oxidation of acetone with alkaline KMnO₄ produces:
a) Acetic acid + Formic acid
b) Acetic acid + CO₂
c) Acetic acid only
d) Propanoic acid

Answer: Acetic acid + Formic acid.

Q113. Which of the following acids is the strongest?
a) Acetic acid
b) Chloroacetic acid
c) Formic acid
d) Trichloroacetic acid

Answer: Trichloroacetic acid. Multiple –Cl atoms increase acidity strongly.

Q114. Reduction of acetic acid with LiAlH₄ gives:
a) Ethane
b) Ethanol
c) Acetaldehyde
d) Propanol

Answer: Ethanol.

Q115. The product of reaction between acetaldehyde and hydroxylamine is:
a) Aldoxime
b) Ketoxime
c) Oxime ether
d) Hydrazone

Answer: Aldoxime.

Q116. Which of the following will give Cannizzaro reaction?
a) Formaldehyde
b) Acetaldehyde
c) Acetone
d) Butanone

Answer: Formaldehyde. (Aldehydes without α-hydrogen give Cannizzaro reaction).

Q117. Acetone on oxidation with K₂Cr₂O₇/H₂SO₄ gives:
a) Acetic acid + Formic acid
b) Acetic acid only
c) Propanoic acid
d) Oxalic acid

Answer: Acetic acid + Formic acid.

Q118. Which of the following aldehydes undergoes Cannizzaro reaction?
a) Acetaldehyde
b) Formaldehyde
c) Benzaldehyde
d) Both (b) and (c)

Answer: Both (b) and (c).

Q119. When acetaldehyde is heated with KOH and iodine, the product is:
a) Chloroform
b) Iodoform
c) Ethanol
d) Acetic acid

Answer: Iodoform (yellow precipitate).

Q120. Which of the following statements is true?
a) Aldehydes are less reactive than ketones
b) Aldehydes are more reactive than ketones
c) Both are equally reactive
d) None

Answer: Aldehydes are more reactive than ketones, due to less steric hindrance and less +I effect.

Q121. Reaction of benzaldehyde with acetic anhydride in presence of sodium acetate is known as:
a) Perkin’s reaction
b) Aldol condensation
c) Friedel–Crafts acylation
d) Cannizzaro reaction

Answer: Perkin’s reaction.

Q122. Which of the following gives positive Tollen’s test?
a) Acetone
b) Benzaldehyde
c) Acetophenone
d) Acetone oxime

Answer: Benzaldehyde.

Q123. The reaction of an aldehyde with two equivalents of a monohydric alcohol in presence of dry HCl gas gives:
a) Acetal
b) Hemiacetal
c) Ester
d) Ether

Answer: Acetal.

Q124. Acetone on treatment with semicarbazide gives:
a) Semicarbazone
b) Hydrazone
c) Oxime
d) Imine

Answer: Semicarbazone.

Q125. Which of the following is least reactive towards nucleophilic addition?
a) Formaldehyde
b) Acetaldehyde
c) Benzaldehyde
d) Acetone

Answer: Benzaldehyde (due to resonance stabilization and lower reactivity).

Q126. Which one of the following does not give iodoform test?
a) Acetone
b) Acetaldehyde
c) Ethanol
d) Formaldehyde

Answer: Formaldehyde.

Q127. Acetaldehyde reacts with NH₃ to form:
a) Hexamethylenetetramine
b) Aldimine
c) Schiff’s base
d) Acetaldoxime

Answer: Aldimine (CH₃CH=NH).

Q128. Which of the following does not give Cannizzaro reaction?
a) Formaldehyde
b) Benzaldehyde
c) Acetaldehyde
d) Trimethylacetaldehyde

Answer: Acetaldehyde (since it has α-hydrogen).

Q129. Which of the following reduces Fehling’s solution?
a) Formaldehyde
b) Acetaldehyde
c) Benzaldehyde
d) Both (a) and (b)

Answer: Both (a) and (b).

Q130. Acetone reacts with HCN in presence of KCN to give:
a) Cyanohydrin
b) Oxime
c) Amide
d) Amine

Answer: Cyanohydrin.

Q131. Which one is the most reactive carbonyl compound?
a) Formaldehyde
b) Acetaldehyde
c) Benzaldehyde
d) Acetone

Answer: Formaldehyde.

Q132. Oxidation of ethanol with acidified KMnO₄ gives:
a) Acetaldehyde
b) Acetic acid
c) Formaldehyde
d) Formic acid

Answer: Acetic acid.

Q133. Which reagent distinguishes between aldehydes and ketones?
a) Fehling’s solution
b) Tollen’s reagent
c) Both (a) and (b)
d) None

Answer: Both (a) and (b).

Q134. Reduction of acetone by NaBH₄ gives:
a) Ethanol
b) Isopropanol
c) Propanol
d) Methanol

Answer: Isopropanol (2-propanol).

Q135. Acetaldehyde undergoes aldol condensation to give:
a) 3-hydroxybutanal
b) Crotonaldehyde
c) Acetic acid
d) Acetone

Answer: 3-hydroxybutanal.

Q136. In the Cannizzaro reaction, the reducing agent is:
a) Aldehyde itself
b) Alcohol
c) Alkali
d) Water

Answer: Aldehyde itself.

Q137. Which one of the following is an α-hydroxy acid?
a) Lactic acid
b) Oxalic acid
c) Acetic acid
d) Formic acid

Answer: Lactic acid.

Q138. Formaldehyde reacts with NH₂OH to form:
a) Oxime
b) Aldoxime
c) Ketoxime
d) Schiff base

Answer: Oxime (formaldoxime).

Q139. Acetic acid reacts with PCl₅ to form:
a) Acetyl chloride
b) Acetone
c) Acetaldehyde
d) Acetic anhydride

Answer: Acetyl chloride.

Q140. Benzaldehyde undergoes Cannizzaro reaction in presence of:
a) Conc. HCl
b) Conc. NaOH
c) Dil. H₂SO₄
d) ZnCl₂

Answer: Conc. NaOH.

Q141. Which of the following compounds undergoes aldol condensation?
a) Acetaldehyde
b) Formaldehyde
c) Benzaldehyde
d) Trimethylacetaldehyde

Answer: Acetaldehyde.

Q142. Formaldehyde reacts with ammonia to give:
a) Urotropine
b) Semicarbazone
c) Oxime
d) Schiff base

Answer: Urotropine (hexamethylenetetramine).

Q143. Reduction of acetone with Zn–Hg/HCl gives:
a) Ethane
b) Propane
c) Butane
d) Methane

Answer: Propane.

Q144. Which compound will not give Cannizzaro reaction?
a) HCHO
b) C₆H₅CHO
c) CH₃CHO
d) p-NO₂C₆H₄CHO

Answer: CH₃CHO.

Q145. The product of reaction between acetic acid and ethanol in presence of conc. H₂SO₄ is:
a) Acetaldehyde
b) Acetone
c) Ethyl acetate
d) Acetyl chloride

Answer: Ethyl acetate (esterification).

Q146. Which of the following acids is strongest?
a) Formic acid
b) Acetic acid
c) Chloroacetic acid
d) Trichloroacetic acid

Answer: Trichloroacetic acid.

Q147. Oxidation of acetaldehyde with KMnO₄ gives:
a) Acetic acid
b) Acetone
c) Methanol
d) Formic acid

Answer: Acetic acid.

Q148. Acetone on reaction with phenylhydrazine gives:
a) Phenylhydrazone
b) Semicarbazone
c) Oxime
d) Hydrazine

Answer: Phenylhydrazone.

Q149. Benzaldehyde reacts with HCN to give:
a) Benzyl alcohol
b) Benzyl cyanide
c) Benzylidene cyanohydrin
d) Benzoic acid

Answer: Benzylidene cyanohydrin.

Q150. Oxidation of formaldehyde with Tollen’s reagent gives:
a) Formic acid
b) CO₂ + H₂O
c) Methanol
d) Acetic acid

Answer: Formic acid.

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