Aldehydes, Ketones and Carboxylic Acids

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

Q31

Which of the following compounds will most readily be dehydrated to give alkene under acidic condition ?

A 1- Pentanol

B 4-Hydroxypentan - 2-one

C 3-Hydroxypentan - 2-one

D 2-Hydroxycyclopentanone

Correct Answer

Option B

Solution

Among those compounds which have most acidic hydrogen will undergo dehydration most readily.

That is why 4 $-$ Hydroxypentan $-$ 2 $-$ one will most readily dehydrated to give unsaturated ketone.

Q32

Which of the following undergoes reaction with 50% sodium hydroxide solution to give the corresponding alcohol and acid?

A Phenol

B Benzoic acid

C Butanal

D Benzaldehyde

Correct Answer

Option D

Solution

This reaction is known as cannizzaro's reaction. In this reaction benzaldehyde in presence of

50\%

NaOH

undergoes disproportionation reaction and from one mol of Benzyl alcohol (Red. product) and one mole of sod. benzoate (ox. product)

Q33

Among the following acids which has the lowest pKa value?

A CH3COOH

B HCOOH

C (CH3)2COOH

D CH3CH2COOH

Correct Answer

Option B

Solution

p{K_a} = - \log \,{K_a};\,\,HCOOH\,\,

is the strongest acid and hence it has the highest

{K_a}

or lowest

p{K_a}

value.

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