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Aldehydes, Ketones and Carboxylic Acids · Question 33

NEET 2017MCQMedium📈 Topic in 25% papers+4−1
1

Consider the reactions, [figure] Identify A, X, Y and Z.

  1. A-Methoxymethane, X-Ethanol, Y-Ethanoic acid, Z-Semicarbazide.
  2. A-Ethanal, X-Ethanol, Y-But-2-enal, Z-Semicarbazone.
  3. A-Ethanol, X-Acetaldehyde, Y-Butanone, Z-Hydrazone.
  4. A-Methoxymethane, X-Ethanoic acid, Y-Acetate ion, Z-Hydrazine.

Answer

(2) A-Ethanal, X-Ethanol, Y-But-2-enal, Z-Semicarbazone.

Solution

∵ X (C2H6O) is dehydrogenated by Cu at 573 K ⇒ X is an alcohol: X = ethanol.

CH3CH2OH [573 K]Cu CH3CHO + H2 ⇒ A = ethanal.

∵ A gives a silver mirror with Tollens' reagent ⇒ A is an aldehyde (confirms ethanal).

Aldol condensation of ethanal on heating with alkali:

2CH3CHO dil. NaOH CH3CH(OH)CH2CHO

CH3CH=CHCHO + H2O ⇒ Y = but-2-enal.

With semicarbazide:

CH3CHO + NH2NHCONH2 CH3CH=NNHCONH2 + H2O ⇒ Z = semicarbazone.

∴ A-Ethanal, X-Ethanol, Y-But-2-enal, Z-Semicarbazone.

Answer: (2)

NEET 2017

Keep practising — Aldehydes, Ketones and Carboxylic Acids

2

Which of the following reagents would distinguish cis-cyclopentane-1,2-diol from the trans-isomer?

  1. MnO2
  2. Aluminium isopropoxide
  3. Acetone
  4. Ozone
NEET 2016 (Phase 1)
3

The product formed by the reaction of an aldehyde with a primary amine is

  1. carboxylic acid
  2. aromatic acid
  3. Schiff's base
  4. ketone
NEET 2016 (Phase 1)
4

The correct order of the strengths of the carboxylic acids [figure] is

  1. I > II > III
  2. II > III > I
  3. III > II > I
  4. II > I > III
NEET 2016 (Phase 2)
5

The correct structure of the product 'A' formed in the reaction [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
NEET 2016 (Phase 2)
6

Reaction of a carbonyl compound with one of the following reagents involves nucleophilic addition followed by elimination of water. The reagent is

  1. hydrazine in presence of feebly acidic solution
  2. hydrocyanic acid
  3. sodium hydrogen sulphate
  4. a Grignard reagent.
AIPMT 2015
7

Which one of the following esters gets hydrolysed most easily under alkaline conditions?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2015
8

Treatment of cyclopentanone [figure] with methyl lithium gives which of the following species ?

  1. Cyclopentanonyl radical
  2. Cyclopentanonyl biradical
  3. Cyclopentanonyl anion
  4. Cyclopentanonyl cation
AIPMT 2015 (Cancelled)
9

An organic compound 'X' having molecular formula C5H10O yields phenylhydrazone and gives negative response to the iodoform test and Tollens' test. It produces n-pentane on reduction. 'X' could be

  1. 3-pentanone
  2. n-amyl alcohol
  3. pentanal
  4. 2-pentanone
AIPMT 2015 (Cancelled)
10

Which one is most reactive towards nucleophilic addition reaction?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2014
11

Reaction by which benzaldehyde cannot be prepared

  1. [figure] + CO + HCl in presence of anhydrous AlCl3
  2. [figure] + Zn/Hg and conc. HCl
  3. [figure] + CrO2Cl2 in CS2 followed by H3O+
  4. [figure] + H2 in presence of Pd-BaSO4
NEET 2013

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