CBSE Class 12 Chemistry Alcohols Phenols and Ethers MCQs Set 06

Question: Catalytic dehydrogenation of a primary alcohol gives a
a) Ketone
b) Aldehyde
c) Sec. alcohol
d) Ester
Answer: b

Question: Ethyl alcohol obtained by fermentation of starch is called wash. What is its purity?
a) 15%
b) 99%
c) 99.9%
d) 95%
Answer: a

Question: Which chemical is used to distinguish between phenol and benzyl alcohol?
a) NaHCO₃
b) FeCl₃
c) Iodoform test
d) none of the above
Answer: b

Question: Which of the following is more acidic than alcohol?
a) Phenol
b) Cyclohexanol
c) Benzyl alcohol
d) Ethenol
Answer: a

Question: Which of the following alcohols is most soluble in water?
a) Propanol
b) Hexanol
c) Pentanol
d) Butanol
Answer: a

Question: Which is most acidic?
a) Phenol
b) 4-nitrophenol
c) Cresol
d) 2-nitrophenol
Answer: d

Question: On heating aqueous solution of benzene diazonium chloride, which compound is formed?
a) Benzene
b) Chloro benzene
c) Phenol
d) Aniline
Answer: c

Question: What is the IUPAC name of Vinyl alcohol?
a) Ethanol
b) Methanol
c) Ethenol
d) Methenol
Answer: c

Question: The reaction of carboxylic acid and alcohol catalysed by conc. H₂SO₄ is called—
a) Dehydration
b) Saponification
c) Esterification
d) Neutralisation
Answer: c

Question: Which compound is obtained by dehydrogenation of secondary alcohols?
a) Ketone
b) Aldehyde
c) Carboxylic acid
d) Amine
Answer: a

ASSERTION – REASONING QUESTIONS

A statement of assertion is followed by a statement of reason. Mark the correct choice from the options given below :
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false.

Question: Assertion : o – Nitrophenol and p – Nitrophenol are separated by steam distillation.
Reason : o-Nitrophenol has intramolecular H – bonding while molecules of p-nitrophenol are linked by intermolecular H – bonding.
Answer: a

Question: Assertion : Phenol is acidic in nature.
Reason : Phenate ion is less resonance stabilised than phenol.
Answer: a

Question: Assertion : Phenols do not react with phosphorus halides while alcohols do not react.
Reason : In phenols C-O bond has partial double bond character due to resonance while it is not so in alcohols.
Answer: a

Question: Assertion : Methyl alcohol is a weaker acid than water.
Reason : Among the aliphatic monohydric alcohols, methyl alcohol is the strongest acid.
Answer: b

One – word answer

Question: Name a compound which can be used as an anesthetic in surgery ?
Answer. Ethrane

Question: In Williamson synthesis , which type of halide should not be used ?
Answer. Tertiary alkylhalide

VERY SHORT ANSWER TYPE QUESTIONS

Question: Why phenol is acidic in nature ?
Answer. Due to stability of phenoxide ion by resonance.

Question: Among HI, HBr and HCl, HI is most reactive towards alcohols. Why ?
Answer. Due to lowest bond dissociation energy of HI.

Question: Name a compound which is used as antiseptic as well as disinfectant.
Answer. Solution of phenol : 0.2% antiseptic, 2% disinfectant.

Question: What is nitrating mixture ?
Answer. Conc. (H₂SO₄ + HNO₃)

Question: Lower alcohols are soluble in water, higher alcohols are not. Why ?
Answer. Due to formation of hydrogen bonds.

Question: Ethanol has higher boiling point than methoxy methane. Give reason.
Answer. Because of H-bonds.

Question: Which of the following isomer is more volatile :
o-nitrophenol or p-nitrophenol
Answer. o-nitrophenol.