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 Multiple Choice QuestionsMultiple Choice Questions

141.

Assertion: Phenol undergoes Kolbe's reaction whereas ethanol does not.

Reason : Phenoxide ion is more basic than ethoxide ion.

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

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

  • If assertion is true but reason is false

  • If both assertion and reason are false.


C.

If assertion is true but reason is false

Phenol undergoes Kolbe's reaction (an electrophilic substitution reaction) because conjugate base (phenoxide ion) is less basic than ethoxide (C2H5O-) ion.


142.

The reaction


Can be classified as

  • Alcohol formation reaction

  • Dehydration reaction

  • Williamson alcohol synthesis reaction

  • Williamson alcohol synthesis reaction


D.

Williamson alcohol synthesis reaction

The formation of ether from alcohol in te presence of base followed by alkylation is known as Williamson ether synthesis reaction.

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143.

Benzoic acid is treated with lithium aluminium hydride. The compound obtained is

  • benzaldehyde

  • benzyl alcohol

  • toluene

  • benzene


B.

benzyl alcohol

When benzoic acid is treated with lithium aluminium hydride, benzyl alcohol is formed. 


144.

In the reaction,

R MgBr + HC(OEt)3 Ether, H3O+ P, the product P is

  • RCHO

  • R2CHOEt

  • R3CH

  • RCH(OEt)2


A.

RCHO

In the above given reaction, the product P is


145.

When a mixture of 1-hexanol and hexanoic acid in diethyl ether is shaken with an aqueous NaHCO3 solution, then which of the following is right distribution?

  • In ether  In sodium bicarbonate solution
    Sodium hexanoate 1- hexanol
  • 1- hexanol Hexanoic acid
  • 1- hexanol Sodium hexanoate
  • Hexanoic acid 1- hexanol

C.

1- hexanol Sodium hexanoate

Hexanoic acid is soluble in ether whereas alcohol is not soluble in NaHCO3 solution.


146.

Assertion : Change in colour of acidic solution of potassium dichromate by breath is used to test drunken drivers.

Reason : Change in colour is due to complexation of alcohol with potassium dichromate.

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

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

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


C.

If assertion is true but reason is false.

Acidified K2Cr2O7 (orange in colour) solution oxidises alcohol and itself gets reduced to Cr2(SO4)3 which is green in colour.


147.

In the given reaction ,

R-OH + HX RX + H2O

the order of reactivity of alcohols is:

  • tertiary < secondary < primary

  • tertiary > secondary > primary

  • tertiary < secondary > primary

  • secondary > primary > tertiary


B.

tertiary > secondary > primary

Reactions of alcohols involving cleavage of C-OH bond follow the reactivity order is tertiary > secondary > primary. With reference to the stability of carbocation intermediate.


148.

The product of the given reacion is


C.

It is a substitution reaction, so the product formed is


149.

The alcohol that produces turbidity immediately with ZnCL2 + conc. HCl at room temperature:

  • 1- hydroxybutane

  • 2- hydroxybutane

  • 2- hydroxy -2- methyl propane

  • 1- hydroxy -2- methyl propane


C.

2- hydroxy -2- methyl propane

(CH3)3CH-OH + HCl Anhydrous ZnCl2+HCl(CH3)3C-Cl +H2O;

3o reacts immediately.

(CH3)3CH-Cl + HClAnhydrous ZnCl2+HCl

(CH3)2CH-Cl + H2O, 2o reacts after 5 min

CH3CH2CH2-OH + HCl Anhydrous ZnCl2+HCl

CH3CH2CH2-Cl + H2O ; 1o reacts only on heating


150.

A compound is soluble in conc. H2SO4 . It does not decolourise bromine in CCL4 but in oxidised by chromic anhydride in aqueous H2SO4 with 2s , turning orange solution to blue green , afterward opaque. The original solution contains :

  • a primary alcohol

  • a secondary alcohol

  • a tertiary alcohol

  • an ether


A.

a primary alcohol

The given compounds is soluble in H2SO4 the compound should be either alcohol or ether. It does not decolourise bromine, which shows that compound does not contain double bond . Compounds is oxidised by chromic anhydride in aqueous H2SO4 i.e. compound does not contain ether group. As the oxidation is very fast, the compound (alcohol) may be a primary alcohol.