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Aldehydes, Ketones and Carboxylic Acids

Multiple Choice Questions

781.

Which of the following gives an aldehyde on dry distillation?

Calcium formate + calcium acetate
Calcium acetate + calcium benzoate
Calcmm acetate
Calcium benzoate

782.

The IUPAC name of

2-methyl-3-bromohexanal
3-bromo-2-methylbutanal
2-methyl-3-bromobutanal
3-bromo-2-methylpentanal

783.

An organic compound 'A' burns with a sooty flame. It is negative towards Tollen's reagent test and positive for Borsche's reagent test. The compound 'A' is

acetophenone
acetone
salicylic acid
benzaldehyde

784.

IUPAC name of H₃C—(OH)CH—CH₂—CHCOOH—CH₃ is

4-hydroxy-1-methyl pentanoic acid
4-hydroxy-2-methyl pentanoic acid
2-hydroxy-4-methyl pentanoic acid
2-hydroxy-2-methyl pentanoic acid

785.

Intramolecular hydrogen bonding is formed in

H₂O
salicyladehyde
NH₃
Benzophenone

786.

The relative acidic strengths of benzoic acid, o-toluic acid and p-toluic acid is of the decreasing order

o-toluic acid > p-toluic acid > benzoic acid
p-toluic acid > benzoic acid > o-toluic acid
o-toluic acid > benzoic acid > p-toluic acid
p-toluic acid > o-toluic acid > benzoic acid

787.

Conversion of benzene to acetophenone can be brought by

wurtz reaction
wurtz- fittig's reaction
Fridel crafts alkylation
Friedel crafts acylation

788.

The compound formed when calcium acetate and calcium formate is distilled

acetone
acetaldehyde
benzaldehyde
acetophenone

789.

Acetone and propanal are

functional isomers
position isomers
geometrical isomers
optical isomers

790.
The reagent used to distinguish between acetaldehyde and benzaldehyde is

Tollen's reagent

Fehling's solution

2-4-dinitrophenyl hydrazine

semicarbazide

Fehling's solution

(i) Reaction with 2,4-dinitrophenylhydrazine ( Brady's reagent).Acetaldehyde and benzaldehyde react wth 2,4-dintrophenylhydrazine (DNP) to form yellow, orange or red ppt of 2,4-dinitrophenylhydrazones (DNP derivatives).

(ii) Reaction with semicarbazide. Both acetaldehyde and benzaldehyde react with semicarbazide to form.

(iii) Reduction of tollen's reagent both acetaldehyde and benzaldehyde reduce.Tollen's reagent to metallic silver which deposit on the walls of the test tube as bnght silver mirror.

$\underset{acetaldehyde}{{CH}_{3} CHO} + \underset{tollen' s reagents}{2 [Ag ({NH}_{3})_{2}]^{+}} + 3 {OH}^{-} \overset{∆}{\to} \underset{acetate ion}{{CH}_{3} {COO}^{-}} + \underset{silver mirror}{2 Ag} ↓ + 4 {NH}_{3} + 2 H_{2} O$

(iv)Reduction of Fehling's solution : Acetaldehyde reduces Fehling solution to a red ppt of cuprous oxide.

$\underset{acetaldehyde}{{CH}_{3} CHO} + {\underset{Fehling' s solution}{2 {Cu}^{2 +} + 5 OH}}^{-} \overset{∆}{\to} \underset{acetate ion}{{CH}_{3} {COO}^{-}} + \underset{Cuprous oxide (red)}{{Cu}_{2} O} + H_{2} O$

However, benzaldehyde does not reduce Fehling's solution.

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Multiple Choice Questions

790. The reagent used to distinguish between acetaldehyde and benzaldehyde is Tollen's reagent Fehling's solution 2-4-dinitrophenyl hydrazine semicarbazide

790.
The reagent used to distinguish between acetaldehyde and benzaldehyde is

Tollen's reagent

Fehling's solution

2-4-dinitrophenyl hydrazine

semicarbazide