Chemistry : Alcohols, Phenols and Ethers

Decreasing order of reactivity in Williamson synthesis of the following :

I. Me₃CCH₂Br

II. CH₃CH₂CH₂Br

III. CH₂=CHCH₂Cl

IV. CH₃CH₂CH₂Cl

• III > II > IV > I

• I > II > IV > III

• II > III > IV > I

• I > III > II > IV

Arrange X, Y and Z in order of increasing acidic strengths.

• X > Z > Y

• Z < X < Y

• X > Y > Z

• Z > X > Y

The pK_a of phenol is 10. Which of the following bases will deprotonate phenol completely?

NaNH₂ (_PK_a of NH₃ = 35) , (_PK_b of H₂O = 16) , NaNH₂ (_pK_a of N${\mathrm{H}}_4^{+}$ = 10) , NaOOCH₃ (_pK_b of CH₃COOH =5)

• NaNH₂

• NH₃

• NaNH₂ and NaOH

• NH₃ and NaOCOCH₃

Assertion : Oxidation of 1-nitronaphthalene gives o-nitrophthalic acid whereas 1-amino naphthalene on oxidation gives phthalic acid.

Reason : An amino group attached to the benzene ring makes it resistant to oxidation whereas nitro group makes the benzene ring susceptible to oxidation.

• 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.

Assertion: Phenol forms 2, 4, 6-tribromophenol on treatment with Br₂- water at 273 K.

Reason : Phenol is o, p- directing group.

• 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

The acidic strength of the given compounds follows the order

I. CH₃-CH=CH-COOH

II. CH₃-$\underset{..}{\overset{..}{\mathrm{O}}}$-CH=CH-COOH

III. CH₃=CH₂-COOH

• II > III > I

• III > II > I

• II > I > III

• I > II > III

The reaction,

C₆H₅ONa + CO₂ +H₂O $\to$C₆H₅OH + NaHCO₃ suggests that

• phenol is a stronger acid than carbonic acid

• carbonic acid is a stronger acid than phenol

• water is a stronger acid than phenol

• None of these.

Phenol , when it first react with cone. sulphuric acid and then with cone. nitric acid gives :

• nitrobenzene

• 2 , 4 , 6 - trinitrobenzene

• o - nitrophenol

• p - nitrophenol

During dehydration of alcohols to alkenes by heating with conc. H₂SO₄ , the initial step is :

• formation of an este

• protonation of alcohol molecule

• formation of carbocation

• elimination of water

Assertion : Phenol is more acidic than ethanol.

Reason : Phenoxide ion is resonance stabilised.

• 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.