JEE Advanced (Fill in the Blanks): Alcohols, Phenols & Ethers | Chapter-wise Tests for JEE Main & Advanced PDF Download

Fill in the Blanks

1. Ethanol vapour is passed over heated copper and the product is treated with aqueous NaOH. The final product is ............... . (1983 - 1 Mark)

Ans: aldol (β-hydroxybutanal)

Solution:

2. The acidity of phenol is due to the ............... of its anion. (1984 - 1 Mark)

Ans: resonance stabilization

3. Formation of phenol from chlorobenzene is an example of ............... aromatic substitution. (1989 - 1 Mark)

Ans: nucleophilic

4. Phenol is acidic because of resonance stabilization of its conjugate base, namely ............... . (1990 - 1 Mark)

Ans: phenoxide ion

5. Aliphatic ethers are purified by shaking with a solution of ferrous salt to remove ............... which are formed on prolonged standing in contact with air. (1992 - 1 Mark)

Ans: peroxides

Solution: On standing in contact with air, ethers are converted into unstable peroxides (R₂O → O) which are highly explosive even in low concentrations. Hence ether
is always purified before distillation. Purification (removal of peroxides) can be done by washing ether with a solution of ferrous salt (which reduces peroxides to alcohols) or by
distillation with conc. H₂SO₄ (which oxidises peroxides)

6. Glycerine contains one .................. hydroxy group. (1997 - 1 Mark)

Ans: secondary

True / False

1. Sodium ethoxide is prepared by reacting ethanol with aqueous sodium hydroxide.

Ans: False

Solution: Ethanol is not acidic enough to react with aq. NaOH. Thus sod. ethoxide (C₂H₅ONa) is prepared by the reaction of Na metal with ethyl alcohol.