Aldehydes, Ketones and Carboxylic Acids Questions — NEET Chemistry

Q1

In a test tube containing a salt, a few drops of dilute

\mathrm{H}_2 \mathrm{SO}_4

was added, which gave colourless vapours having the smell of vinegar. The vapours turned the blue litmus paper red. Identify the correct anion from the following :

A Sulphide,

\mathrm{S}^{2-}

B Sulphate,

\mathrm{SO}_4^{2-}

C Acetate,

\mathrm{CH}_3 \mathrm{COO}^{-}

D Carbonate,

\mathrm{CO}_3^{2-}

Correct Answer

Option C

Solution

\text{ So, correct Answer is : Acetate, } \mathrm{CH}_3 \mathrm{COO}^{-}

Q2

Identify the suitable reagent for the following conversion.

A (i)

\mathrm{NaBH}_4

, (ii)

\mathrm{H}^{+} / \mathrm{H}_2 \mathrm{O}

B

\quad \mathrm{H}_2 / \mathrm{Pd}-\mathrm{BaSO}_4

C (i)

\mathrm{LiAlH}_4

, (ii)

\mathrm{H}^{+} / \mathrm{H}_2 \mathrm{O}

D (i)

\mathrm{AlH}(\mathrm{iBu})_2

, (ii)

\mathrm{H}_2 \mathrm{O}

Correct Answer

Option D

Solution

Esters are reduced to aldehydes with DIBAL-H

Q3

The correct order of decreasing acidity of the following aliphatic acids is

A

\mathrm{HCOOH}>\mathrm{CH}_3 \mathrm{COOH}>\left(\mathrm{CH}_3\right)_2 \mathrm{CHCOOH}>\left(\mathrm{CH}_3\right)_3 \mathrm{CCOOH}

B

\mathrm{HCOOH}>\left(\mathrm{CH}_3\right)_3 \mathrm{CCOOH}>\left(\mathrm{CH}_3\right)_2 \mathrm{CHCOOH}>\mathrm{CH}_3 \mathrm{COOH}

C

\left(\mathrm{CH}_3\right)_3 \mathrm{CCOOH}>\left(\mathrm{CH}_3\right)_2 \mathrm{CHCOOH}>\mathrm{CH}_3 \mathrm{COOH}>\mathrm{HCOOH}

D

\mathrm{CH}_3 \mathrm{COOH}>\left(\mathrm{CH}_3\right)_2 \mathrm{CHCOOH}>\left(\mathrm{CH}_3\right)_3 \mathrm{CCOOH}>\mathrm{HCOOH}

Correct Answer

Option A

Solution

Electron donating group decreases the acidity of carboxylic acids. So correct order is

\mathrm{HCOOH}>\mathrm{CH}_3 \mathrm{COOH}>\left(\mathrm{CH}_3\right)_2 \mathrm{CHCOOH}>\left(\mathrm{CH}_3\right)_3 \mathrm{CCOOH}

Q4

The following conversion is known as:

A Stephen reaction

B Gattermann-Koch reaction

C Etard reaction

D Rosenmund reaction

Correct Answer

Option D

Solution

Rosenmund reaction

Q5

Which of the following reactions is not an example for nucleophilic addition-elimination reaction?

A CH 3 CHO + NH 3

\rightleftharpoons

CH 3 CH = NH + H 2 O

B

C CH 3 CHO + NH 2 OH

\rightleftharpoons

CH 3 CH = N

-

OH + H 2 O

D CH 3 CHO + C 6 H 5 NHNH 2

\rightleftharpoons

CH 3 CH = N

-

NHC 6 H 5 + H 2 O

Correct Answer

Option B

Solution

It is an example of nucleophilic addition reaction

Q6

RMgX + CO 2

\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{ether}^{dry}}

Y

\overset{{{H_3}{O^ + }}}\longrightarrow

RCOOH What is Y in the above reaction?

A RCOO

-

Mg + X

B R 3 CO

-

Mg + X

C RCOO

-

X +

D (RCOO) 2 Mg

Correct Answer

Option A

Solution

Here Y is RCOO $-$ Mg + X

Q7

Compound X on reaction with O 3 followed by Zn/H 2 O gives formaldehyde and 2-methyl propanal as products. The compound X is

A 3-Methylbut-1-ene

B 2-Methylbut-1-ene

C 2-Methylbut-2-ene

D Pent-2-ene

Correct Answer

Option A

Solution

The given reaction is the reductive ozonolysis of an alkene. The alkene will be

Q8

What is the IUPAC name of the organic compound formed in the following chemical reaction?

A 2-methylbutan-2-ol

B 2-methylpropan-2-ol

C pentan-2-ol

D pentan-3-ol

Correct Answer

Option A

Solution

IUPAC name of product is 2-methylbutan-2-ol.

Q9

Consider the above reaction and identify the missing reagent/chemical.

A DIBAL-H

B B 2 H 6

C Red Phosphorus

D CaO

Correct Answer

Option D

Solution

In this reaction, removal of carbon dioxide takes place.

So, this is a decarboxylation reaction.

A decarboxylation reaction takes place with soda lime (NaOH + CaO).

So, missing reagent is CaO.

Q10

Reaction between benzaldehyde and acetophenone in presence of dilute NaOH is known as :

A Cannizzaro's reaction

B Cross Cannizzaro's reaction

C Cross Aldol condensation

D Aldol condensation

Correct Answer

Option C

Solution

In the presence of dil. OH - , benzaldehyde and acetophenone will react to undergo cross-aldol condensation.