CBSE Class 12 Chemistry Aldehydes Ketones and Carboxylic Acids MCQs Set E

Question. Propanal and propanone, both have same molecular formula(C₃H₆O), what do you expect about their boiling points?
(a) Both have same boiling point
(b) Boiling point of propanal is higher than the boiling point of propanone.
(c) Boiling point of propanal is lower than the boiling point of propanone
(d) Nothing can be predicted
Answer: c

Question. Which one of the following on oxidation gives a ketone ?
(a) Primary alcohol
(b) Secondary alcohol
(c) Tertiary alcohol
(d) All of these
Answer: b

Question. 2-pentanone and 3-pentanone can be distinguished by :
(a) Cannizaro’s reaction
(b) Aldol condensation
(c) Iodoform reaction
(d) Clemmensen’s reduction
Answer: c

Question. If formaldehyde and KOH are heated, then we get
(a) methane
(b) methyl alcohol
(c) ethyl formate
(d) acetylene
Answer: b

Question. The reagent which can be used to distinguish acetophenone from benzophenone is
(a) 2,4- dinitrophenylhydrazine
(b) aqueous solution of NaHSO₃
(c) benedict reagent
(d) I₂and Na₂CO₃
Answer: d

Question. The IUPAC name of the compound having the molecular formula Cl₃C –CH₂CHO is
(a) 3, 3, 3- trichloropropanal
(b) 1, 1, 1- trichloropropanal
(c) 2, 2, 2- trichloropropanal
(d) Chloral
Answer: a

Question. Less reactivity of ketone is due to
(a) + I inductive effect decrease positive charge on carbonyl carbon atom
(b) steric effect of two bulky alkyl groups
(c) sp² hybridised carbon atom of carbonyl carbon atom
(d) Both (a) and (b)
Answer: d

Question. Benzaldehyde reacts with ethanoic KCN to give
(a) C₆H₅CHOHCN
(b) C₆H₅CHOHCOC₆H₅
(c) C₆H₅CHOHCOOH
(d) C₆H₅CHOHCHOHC₆H₅
Answer: b

Question. Which of the following contain an aldehyde?
(a) Vanilla beans
(b) Meadow sweet
(c) Cinnamon
(d) All of these
Answer: d

Question. Which of the following have pleasant smell?
(a) Methanal
(b) Propanal
(c) Ethanal
(d) Hexanal
Answer: d

Question. The catalyst used in Rosenmund’s reduction is
(a) HgSO₄
(b) Pd/BaSO₄
(c) anhydrous AlCl₃
(d) anhydrous ZnCl₂
Answer: b

Question. Clemmensen reduction of a ketone is carried out in the presence of which of the following ?
(a) Glycol with KOH
(b) Zn-Hg with HCl
(c) LiAlH₄
(d) H₂ and Pt as catalyst
Answer: b

Question. Carbonyl compounds undergo nucleophilic addition because of
(a) electronegativity difference of carbon and oxygen atoms
(b) electromeric effect
(c) more stable anion with negative charge on oxygen atom and less stable carbonium ion
(d) None of the above
Answer: b

Question. Which of the following is used to prepare ketone from acyl chloride ?
(a) R-MgX
(b) R₂Cd
(c) CO + HCl
(d) CrO₃
Answer: b

Question. Aldehydes and ketones are distinguished by which of the following test ?
(a) Lucas test
(b) Tollen’s test
(c) KMnO₄ solution (Baeyer’s test)
(d) None of these
Answer: b

Question.The product formed in Aldol condensation is
(a) a beta-hydroxy aldehyde or a beta-hydroxy ketone
(b) an alpha-hydroxy aldehyde or ketone
(c) an alpha, beta unsaturated ester
(d) a beta-hydroxy acid
Answer: a

Question. The most appropriate reagent to distinguish between acetaldehyde and formaldehyde is :
(a) Fehling’s solution
(b) Tollen’s reagent
(c) Schiff’s reagent
(d) Iodine in presence of base
Answer: d

Question.Which of the following statement is false ?
(a) Cannizzaro reaction is given by aldehydes in presence of alkali
(b) Aldol condensation is given by aldehydes in presence of alkali
(c) Aldol condensation is given by aldehydes and ketones in presence of acids
(d) None of the above
Answer: d

Question. Iodoform test is not given by
(a) 2-Pentanone
(b) Ethanol
(c) Ethanal
(d) 3-Pentanone
Answer: d

Question. Phenylmethyl ketone can be converted into ethylbenzene in one step by which of the following reagents?
(a) LiAlH₄
(b) Zn-Hg/HCl
(c) NaBH₄
(d) CH₃MgI
Answer: b

Question. Aldol condensation would not occur in :
(a) CH₃COCH₃
(b) CH₃CH₂CHO
(c) HCHO
(d) CH₃CHO
Answer: c

Question. What is formed when a primary alcohol undergoes catalytic dehydrogenation ?
(a) Aldehyde
(b) Ketone
(c) Alkene
(d) Acid
Answer: a

Question. Ketone upon treatment with Grignard Reagent gives
(a) primary alcohol
(b) secondary alcohol
(c) tertiary alcohol
(d) aldehyde
Answer: c

Question. Which one of the following can be oxidised to the corresponding carbonyl compound?
(a) 2-hydroxy-propane
(b) Ortho-nitrophenol
(c) Phenol
(d) 2-methyl-2 hydroxy-propane
Answer: a

Question. The oxidation of toluene to benzaldehyde by chromyl chloride is called
(a) Rosenmund reaction
(b) Wurtz reaction
(c) Etard reaction
(d) Fittig reaction
Answer: c

Question. A compound does not react with 2, 4-dinitrophenylhydrazine, the compound is :
(a) Acetone
(b) Acetaldehdye
(c) CH₃OH
(d) CH₃CH₂COCH₃
Answer: c

CRITICAL THINKING TYPE QUESTIONS

Question. Which of the following is correct order of acidity?
(a) HCOOH > CH₃COOH > ClCH₂COOH > C₂H₅ COOH
(b) ClCH₂COOH > HCOOH > CH₃COOH > C₂H₅COOH
(c) CH₃COOH > HCOOH > ClCH₂COOH > C₂H₅COOH
(d) C₂H5COOH > CH₃COOH > HCOOH > ClCH₂COOH
Answer: b

Question. Which of the following reagent reacts in different ways with CH₃CHO, HCHO and C₆H₅CHO ?
(a) Fehling solution
(b) C₆H₅NHNH₂
(c) Ammonia
(d) HCl
Answer: c

Question. An organic compound of formula, C₃H₆O forms phenyl hydrazone, but gives negative Tollen’s test. The compound is
(a) CH₃CH₂COCH₃
(b) CH₃CH₂CHO
(c) CH₃COCH₃
(d) Both (a) and (c)
Answer: d

Question. Aldehydes and ketones will not form crystalline derivatives with
(a) sodium bisulphite
(b) phenylhydrazine
(c) semicarbazide hydrochloride
(d) dihydrogen sodium phosphate.
Answer: d

Question. A compound C₅H₁₀O forms orange–red precipitate upon reaction with 2,4–DNP, but does not give positive Tollen’s test and iodoform test. Possible compound is
(a) 2, 2–dimethylpropanal
(b) 3–methylbutan–2–one
(c) Pentan–3–one
(d) None of the above
Answer: c

Question. Suppose the reaction of compound containing ketone as functional group is carried in basic medium of NaOH. Which of the following will one use to protect the unwanted reaction due presence of carbonyl moiety.
(a) NaHSO₃
(b) HCN
(c) ethylene glycol and HCl
(d) None of these
Answer: c

Question. Which of the following compound will undergo self aldol condensation in the presence of cold dilute alkali ?
(a) CH₂=CH—CHO
(b) CH≡C—CHO
(c) C₆H5CHO
(d) CH₃CH₂CHO.
Answer: d

Question. When ethanal reacts with propanal in the presence of a base, the number of products formed is
(a) 2
(b) 3
(c) 4
(d) 5
Answer: c

Question. Which of the following represents the correct order of the acidity in the given compounds?
(a) FCH₂COOH > CH₃COOH > BrCH₂COOH > ClCH₂COOH
(b) BrCH₂COOH > ClCH₂COOH > FCH₂COOH > CH₃COOH
(c) FCH₂COOH > ClCH₂COOH > BrCH₂COOH > CH₃COOH
(d) CH₃ COOH > BrCH₂COOH > ClCH₂COOH > FCH₂COOH
Answer: c

Question. In the crossed Cannizzaro reaction involving HCHO as one of the components
(a) HCHO is always oxidised because of electronic effect
(b) HCHO is always oxidised because of steric effect
(c) both of the above statements are true
(d) none of the above statement is true
Answer: c