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Aldehydes, Ketones and Carboxylic Acids

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

Keep practising — Aldehydes, Ketones and Carboxylic Acids

Ques. 2NEET 2016 (Phase 1)

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
Ques. 3NEET 2016 (Phase 2)

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
Ques. 4NEET 2016 (Phase 2)

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

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 5AIPMT 2015

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.
Ques. 6AIPMT 2015

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

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 7AIPMT 2015 (Cancelled)

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
Ques. 8AIPMT 2015 (Cancelled)

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
Ques. 9AIPMT 2014

Which one is most reactive towards nucleophilic addition reaction?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 10NEET 2013

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
Ques. 11NEET 2013 (Karnataka)

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

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