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Aldehydes, Ketones and Carboxylic Acids, , , , Multiple Choice Questions (1 Mark), , , , 1. Which of the following is the product of reaction of ethane nitrile with, Grignard reagent followed by acid hydrolysis?, (A) A ketone (B) Analdehyde, (C) Anacid (D) An acid chloride, , Hint: For example,, , H3C — C= N + H3CMgCl —*“*-> CH; — C = NMgCl —8°, CH;COCH; + NH; + Mg(CI)OH, |, , Ethanenitrile H;C Acetone, 2. reaction is used to synthesize straight alkyl substituted, benzenes., (A) Etard (B) Rosenmund reduction, (C) Stephen reaction (D) Wolf Kishner reduction, , 3. Ketones CANNOT be converted into carboxylic acid using, (A) Alkaline KMnO, (B) CrO;, (C) dil. HNO, (D) hot and conc. HNO;, , 4. CORRECT order of acid strength for, , 1, acetic acid, , ii. fluoroacetic acid Kal a} M, iii. 4-nitrobenzoic acid P ., iv. 4-methyl benzoic acid is, , (A) i> ii> iii > iv (B) ii>iii>iv>i, (C) iti>iv>i>ii (D) iv>i>ii> iii, 3. Addition of sodium bisulphite to ethanal is type of reaction., , (A) _ electrophilic addition (B) electrophilic substitution, (C) nucleophilic addition (D) nucleophilic substitution, , 6. The following reactants CANNOT be converted into carboxylic acid., , , , (A) Dry ice (B) Cyclohexane, (C) Toluene (D) Cyclohexene, Std. XII Sci.: Chemistry, , iz

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Chapter 12: Aldehydes, Ketones and Carboxylic Acids 1a rget Publications’ Pvt. Ltd., , , , , , 7. The following compounds will give positive Fehling’s test., (A) Propanone (B) Pentan-3-one, (C) Butanone (D) Butanal, [Note: Option (D) is modified by replacing ‘Butan-2-ol’ with ‘Butanal’.], , Very Short Answer Questions (1 Mark), , , , 1. Write IUPAC name of phthalaldehyde?, Ans: IUPAC name of phthalaldehyde: Benzene-1,2-dicarbaldehyde, , 2s What is substituted imine called?, Ans: The substituted imine is called a Schiff's base., , 3. | Write the name of the product obtained when ketones react with, 1,2-diol in presence of dry HCI., , Ans: The product obtained when ketones react with 1,2-diol in presence of, dry HCI is known as cyclic ketal., , 4. Write another name of disproportionation reaction?, Ans: Cannizzaro reaction, , 5. | Write the number of products when a mixture of ethanal and, propanal is reacted with dilute alkali?, , Ans: A mixture of ethanal and propanal on reaction with dilute alkali gives a, mixture of four products., , 6. Write structure of the product formed when carboxylic acid is, heated with dehydrating agent like POs., , Ans: Mono carboxylic acids on heating with strong dehydrating agent like, POs, give acid anhydrides. The structure of acid anhydride is,, , O, nt, eK, oO, , “a, a, a O, Acid anhydride, , 7. Write the reducing agent which CANNOT reduce -COOH group., Ans: Sodium borohydride (NaBH,) does not reduce -COOH group., , , , Std. XII Sci.: Chemistry 2

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Chapter 12: Aldehydes, Ketones and Carboxylic Acids Target Publications” Pvt. Ltd., , , , , , Ans:, , 2., Ans:, , Short Answer Questions (Type-!) (2 Marks), , , , Write Classification of aliphatic ketones with suitable example., , On the basis of types of alkyl groups bonded to carbonyl carbon,, aliphatic ketones are further classified as simple and mixed ketones., Simple or symmetrical ketones: The ketones in which both the alkyl, groups bonded to carbonyl carbon are identical, are called simple, ketones or symmetrical ketones., , e.g. O O, I I, H3C —C— CH; HsC, — C — C)Hs, Dimethyl ketone (Acetone) Diethyl ketone, , Mixed or unsymmetrical ketones: The ketones in which two alkyl, groups bonded to carbonyl carbon are different, are called mixed, ketones or unsymmetrical ketones., , eg. oO oO, I I, HsC, — C — CH; HsC2 — C — CH2— CH2 — CH;, Ethyl methyl ketone Ethyl n-propyl ketone, , What is the action of Grignard reagent on benzonitrile?, Benzonitrile on reaction with Grignard reagent in dry ether as solvent, followed by acid hydrolysis will form corresponding ketone derivative., , Co6Hs -C=N + RMgX —*“>5 R-C=NMgX —#°_, RCO — CoHs + NH; + Mg(X)OH, , Benzonitrile Alkyl magnesium | Ketone derivative, , halide CoHs, (Grignard reagent), , , , 3. Carboxylic acids have higher boiling points than those of ethers., Give reason., , Ans:, , i. In liquid phase, carboxylic acids form dimer in which two molecules are, held by two hydrogen bonds., , ii. Acidic hydrogen of one molecule form hydrogen bond with carbonyl, oxygen of the other molecule., , iii. This doubles the size of the molecule resulting in increase in, intermolecular van der Waals forces, which in turn results in high, boiling point., , iv. Therefore, carboxylic acids have higher boiling points than those of, ethers of comparable mass., , Std. XII Sci.: Chemistry

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Chapter 12: Aldehydes, Ketones and Carboxylic Acids Ta rget Publications” Pvt. Ltd., , , , , , e.g., , Ans:, , H3CH), , H, , Propanal, , ii., , Explain Cannizzaro reaction with suitable example., , : Cannizzaro reaction:, , This reaction is given only by aldehydes having no a-hydrogen atom., Aldehydes undergo disproportionation reaction that is, self -oxidation, and reduction reaction on heating with concentrated alkali., , In Cannizzaro reaction, one molecule of an aldehyde is reduced to, alcohol and at the same time, second molecule is oxidized to carboxylic, acid salt., , 1 i I, 2H-C-H + NaOH —+-+, H—-C-O Na’ + H—C-—OH, Formaldehyde Sodium Sodium formate |, , hydroxide (50%) H, Methanol, , What is the action of following on propanal?, Hydroxyl amine ii. Hydrazine, , Hydroxyl amine: Propanal will undergo addition elimination reaction, with hydroxyl amine to give corresponding oxime derivative containing, C=N bonds (imine)., , H H, , |, C=0O+NH;—OH = =]H3;CH2C —-C—N-OH |—.> H3CH2C -C = N- OH, , -H,O, | Oxime derivative, Hydroxylamine OH H, , Hydrazine: Propanal will undergo addition elimination reaction with, hydrazine to give corresponding hydrazone derivative containing, C=N bond (imine)., , H H, , |, H;CH,C — C =O + HN — NH2 — H;CH,C — C = N —- NH, + HO, , Propanal Hydrazine Hydrazone derivative, , , , 6. Write the preparation reactions for acid amide from the following., , i. Carboxylic acid ii. Acid chloride, , Ans:, , ds Carboxylic acids react with ammonia to from ammonium carboxylate, salt which on further strong heating at high temperature decomposes to, give acid amide., , Std. XII Sci.: Chemistry

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Chapter 12: Aldehydes, Ketones and Carboxylic Acids Ta ret Publications” Pvt. Ltd., , , , , , ? r I, R-C-OH+NH; == R-C-O -NH{i —*> R-C-NH,, Carboxylic acid Ammonium carboxylate —~ Hae Acid amide, , ii. Acid amide is formed by reacting acid chloride with ammonia., , R—COCI + NH; —> R — CONH; + HCl, Acyl chloride Acid amide, , Short Answer Questions (Type-ll) (3 Marks), , , , 1. What is the action of following reagents on ethanoic acid?, , i. SOCL/heat ii. Sodalime/heat, iii. P,O,/heat, Ans:, , i. SOCL/heat: Ethanoic acid on heating with SOCl, gives the, corresponding acyl chloride., , CH;COOH + SOCL —*>» CH;COCI + HCIT + so,t, Ethanoic acid — Thiony| chloride Acetyl chloride, , ii. Sodalime/heat: Sodium salts of ethanoic acid on heating with soda lime, give methane which contain one carbon atom less than the ethanoic, , acid., CH;—COOH —“", CH;—COONa* + NaOH Oey CH, + NazCO;, Ethanoic acid Sodium acetate Methane, , iii. P,O;/heat: Ethanoic acid on heating with strong dehydrating agent P.O;, forms acetic anhydride., O oO, I I, 2CH;COOH —2%", CH;—-C-O-C-—CH;+H,0, , Ethanoic acid Acetic anhydride, , 2. Explain aldol condensation reaction in details., , Ans: Aldol condensation:, , i. Aldehydes containing at least one o—hydrogen atom undergo a reaction in, presence of dilute alkali (dilute NaOH, KOH or Na,CO;) as catalyst to form, B-hydroxy aldehydes (aldol). This reaction is known as aldol reaction., , ii. | Formation of aldol is an addition reaction., , , , Std. XII Sci.: Chemistry 5