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Alcohols, Phenols and Ethers

Multiple Choice Questions

Phenol , in Liebermann's nitroso test , give the colour :

red
yellow
blue
pink

blue

Phenol gives Liebermann's nitroso test to give deep blue colour due to the formation of sodium salt of indophenol .

Phenol $\to_{conc . H_{2} {SO}_{4}}^{{NaNO}_{2}}$ Blue $\overset{HOH}{\to}$ Red $\overset{NaOH}{\to}$

Assertion: Phenol is a weaker acid than ethanol.
Reason: Groups with +M effect and -I effect decrease acidity at m-position.

If both assertion and reason are true and reason is a correct explanation of the assertion.
If both the assertion and reason are true but the reason is not a correct explanation of the assertion.
If the assertion is true but the reason is false.
If both the assertion and reason are false.

If both the assertion and reason are false.

Phenol is a stronger acid than ethanol. This is due to the resonance stabilization of the phenolate ion which is produced after deprotonation.

But there is no such stabilization in the case of ethanol.

C₂H₅OH $⇌$ C₂H₅O^- + H⁺

The groups with +M and -I effect to decrease the acidity at p-position, but at m-position, the acidity is increased due to -I effect.

Assertion: Ethers behave as bases in the presence of mineral acids.

Reason: It is due to the presence of a lone pair of electrons on the oxygen.

If both assertion and reason are true and the reason is a correct explanation of the assertion.
If both the assertion and reason are true but the reason is not a correct explanation of the assertion.
If the assertion is true but the reason is false.
If both the assertion and reason are false.

If both assertion and reason are true and the reason is a correct explanation of the assertion.

Due to the presence of lone pair of electrons on the oxygen atom, ethers behave as the base and form stable oxonium salts with mineral acids.

A sample of CHCl₃ before using as an anaesthetic is tested by

AgNO₃ solution after boiling with KOH
Ammonical cuprous chloride
Fehling solution
AgNO₃

AgNO₃

Before using CHCl₃ as an anaesthetic, it is treated with aqueous solution of AgNO₃. A pure sample does not give ppt with aqueous AgNO₃.

Dehydration of alcohol involves

carbene
carbanion
free radical
carbonium ion

carbonium ion

The dehydration reaction of alcohols to generate alkene proceeds by heating the alcohols in the presence of a strong acid, such as sulfuric or phosphoric acid, at high temperatures. It involves carbonium ion in its mechanism.

What is the name of reaction when benzaldehyde changes in to benzyl alcohol?

Cannizzaro's reaction
Wurtz reaction
Kolbe reaction
Friedel-Craft's reaction

Cannizzaro's reaction

Cannizzaro's reaction is the reaction where benzaldehyde changes in to benzyl alcohol.

Aniline on treatment with HCl and NaNO₂ gives

diazo salt
nitroaniline
chloroaniline
aminophenol

diazo salt

When aniline is treated with HCl and NaNO₂,it forms benzene diazonium chloride. Therefore, it gives diazo salt.

What will be the product ,when carboxy phenol ,obtained by Reimer Tiemann's process ,is deoxidised with Zn powder ?

Phenol gives salicylic acid in Reimer Tiemann reaction ,which on deoxidation with Zn powder ,give benzoic acid .

Which of following is the correct order of increasing reactivity?

RCOOR' < RCOCl < RCONH₂
RCOOR' < RCONH₂ < RCOCl
RCOCl < RCONH₂ < RCOOR'
RCONH₂ < RCOOR' < RCOCl

RCONH₂ < RCOOR' < RCOCl

Among all the given options, option c has the correct order of increasing reactivity.

RCOCl (Acid halide) < RCONH₂ (Amide) < RCOOR (Ester)

10.

Gammexane is

benzene hexachloride
bromo benzene
benzyl chloride
chlorobenzene

benzene hexachloride

Gammexane is benzene hexachloride. Its IUPAC name is 1,2,3,4,5,6-hexachlorocyclohexane.