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Aldehydes, Ketones and Carboxylic Acids · Question 34

NEET 2016 (Phase 1)MCQHard📈 Topic in 38% papers+4−1
1

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

Answer

(3) Acetone

Solution

As per NCERT, a ketone reacts with a 1,2-diol (e.g. ethylene glycol) to form a cyclic ketal.

In cis-cyclopentane-1,2-diol both –OH groups are on the same side of the ring ⇒ they can bridge to the carbonyl carbon of acetone ⇒ a cyclic ketal (acetonide) is formed.

In the trans-isomer the two –OH groups are on opposite sides of the rigid ring ⇒ a fused five-membered ring cannot form ⇒ no reaction.

MnO2, aluminium isopropoxide and ozone do not distinguish between the two isomers.

∴ Acetone distinguishes cis-cyclopentane-1,2-diol from the trans-isomer.

Answer: (3)

NEET 2016 (Phase 1)

Keep practising — Aldehydes, Ketones and Carboxylic Acids

2

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)
3

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)
4

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

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
NEET 2016 (Phase 2)
5

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
6

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

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2015
7

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)
8

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)
9

Which one is most reactive towards nucleophilic addition reaction?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2014
10

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
11

In the following reaction: HC CH [Hg2+]H2SO4 'P' Product 'P' will not give

  1. Tollen's reagent test
  2. Brady's reagent test
  3. Victor Meyer test
  4. Iodoform test
NEET 2013 (Karnataka)

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