Aldehydes, Ketones and Carboxylic Acids

JEE Chemistry · 33 questions · Page 2 of 4 · Click an option or "Show Solution" to reveal answer

Q11

The increasing order of the rate of HCN addition to compounds A – D is (A) HCHO (B) CH3COCH3 (C) PhCOCH3 (D) PhCOPh

A A < B < C < D

B D < B < C < A

C D < C < B < A

D C < D < B < A

Correct Answer

Option C

Solution

NOTE : Addition of

HCN

to carbonyl compounds is nucleophilic addition reaction.

The order of reactivity of carbonyl compounds is Aldehydes (smaller to higher) Ketones (smaller to higher), Then

HCHO > C{H_3}COC{H_3} > Ph.COC{H_3} > PhCOPh

$ NOTE : The lower reactivity of Ketones is due to presence of two alkyl group which shows

+ {\rm I}

effect. The reactivity of Ketones decreases as the size of alkyl group increases.

Q12

The compound formed as a result of oxidation of ethyl benzene by KMnO4 is :

A benzophenone

B acetophenone

C benzoic acid

D benzyl alcohol

Correct Answer

Option C

Solution

When alkyl benzene are oxidised with alkaline

KMn{O_4},

(strong oxidising agent) the entire alkyl group is oxidised to

-COOH

group regardless of length of side chain.

Q13

A liquid was mixed with ethanol and a drop of concentrated H2SO4 was added. A compound with a fruity smell was formed. The liquid was :

A CH3OH

B HCHO

C CH3CO CH3

D CH3COOH

Correct Answer

Option D

Solution

Fruity smell is due to ester formation which is formed between ethanol and acid.

Q14

One mole of a symmetrical alkene on ozonolysis gives two moles of an aldehyde having a molecular mass of 44 u. The alkene is

A propene

B 1–butene

C 2–butene

D ethene

Correct Answer

Option C

Solution

The given molecular formula suggests that the aldehyde formed will be acetaldehyde hence the alkene will be

Q15

The strongest acid amongst the following compounds is :

A HCOOH

B CH3CH2CH(Cl)CO2H

C ClCH2CH2CH2COOH

D CH3COOH

Correct Answer

Option B

Solution

The electron withdrawing

\left( { - {\rm I}} \right)

group

- Cl

withdraws electrons from

O-H

bond and thus helps the cleavage of the

O-H

bond releasing hydrogen as

{H^ + }.

Q16

Trichloroacetaldehyde was subjected to Cannizzaro’s reaction by using NaOH. The mixture of the products contains sodium trichloroacetate and another compound. The other compound is :

A Trichloromethanol

B 2, 2, 2-Trichloropropanol

C Chloroform

D 2, 2, 2-Trichloroethanol

Correct Answer

Option D

Solution

In Cannizzaro's reaction the compounds which do not contain $\alpha$ -hydrogen atoms undergo oxidation and reduction simultaneously i.e. undergo disproportionation and form one molecule of sodium salt of carboxylic acid as oxidation product and one molecule of alcohol as reduction product.

Q17

The increasing order of the reactivity of the following compound in nucleophilic addition reaction is : Propanal, Benzaldehyde, Propanone, Butanone

A Butanone < Propanone < Benzaldehyde < Propanal

B Benzaldehyde < Butanone < Propanone < Propanal

C Propanal < Propanone < Butanone < Benzaldehyde

D Benzaldehyde < Propanal < Propanone < Butanone

Correct Answer

Option A

Solution

Rate of Nucleophilic addition : 1.

Aldehyde > Ketone 2.

Aliphatic aldehyde > Aromatic aldehyde $\therefore$ Correct order of nucleophilic addition reaction is :

Q18

The predominant intermolecular forces present in ethyl acetate, a liquid, are:

A Dipole-dipole and hydrogen bonding

B hydrogen bonding and London dispersion

C London dispersion, dipole-dipole and hydrogen bonding

D London dispersion and dipole-dipole

Correct Answer

Option D

Solution

Ethyl acetate (CH3COOCH2CH3) is an organic compound with a molecular structure that does not include any hydrogen atoms bonded directly to highly electronegative atoms like nitrogen, oxygen, or fluorine.

Because of this, it cannot form hydrogen bonds.

However, ethyl acetate does possess a polar carbonyl group (C=O), which contributes to dipole-dipole interactions, and like all molecules, it can experience London dispersion forces.

Therefore, the predominant intermolecular forces present in ethyl acetate are dipole-dipole interactions and London dispersion forces.

Hence, the correct option is : Option D: London dispersion and dipole-dipole

Q19

Which of the following reagent is used for the following reaction ?

\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}_3 \stackrel{?}{\longrightarrow} \mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CHO}

A Molybdenum oxide

B Manganese acetate

C Copper at high temperature and pressure

D Potassium permanganate

Correct Answer

Option A

Solution

Molybdenum oxide (Mo2O3 ) is used for oxidising alkanes to aldehyde.

It used to manufacture molybdenum metal, which serves as an additive to steel and corrosive resistant alloys.

Q20

Given below are two statements : Statement I : The nucleophilic addition of sodium hydrogen sulphite to an aldehyde or a ketone involves proton transfer to form a stable ion. Statement II : The nucleophilic addition of hydrogen cyanide to an aldehyde or a ketone yields amine as final product. In the light of the above statements, choose the most appropriate answer from the options given below :

A Both Statement I and Statement are true.

B Statement I is true but Statement II is false.

C Statement I is false but Statement II is true.

D Both Statement I and Statement II are false.

Correct Answer

Option B

Solution

Statement I : Correct Statement II : Wrong

Ready for a full JEE mock test? Timed · full syllabus · instant results

Take a Mock Test →