Alcohol, Phenol and Ether MCQ Questions & Answers in Organic Chemistry | Chemistry
Learn Alcohol, Phenol and Ether MCQ questions & answers in Organic Chemistry are available for students perparing for IIT-JEE, NEET, Engineering and Medical Enternace exam.
31.
Which of the following compounds will react with sodium hydroxide solution in water?
A
$${C_6}{H_5}OH$$
B
$${C_6}{H_5}C{H_2}OH$$
C
$${\left( {C{H_3}} \right)_3}COH$$
D
$${C_2}{H_5}OH$$
Answer :
$${C_6}{H_5}OH$$
Phenol $$\left( {{C_6}{H_5}OH} \right)$$ will react with sodium hydroxide solution in water, as phenols are more acidic than alcohols.
32.
Which of the following are the products shown by the reaction of methoxyethane with $$HI?$$
A
$${C_2}{H_5}I + C{H_3}OH$$
B
$$C{H_3}I + {H_2}O$$
C
$${C_2}{H_5}OH + {H_2}O$$
D
$${C_2}{H_5}OH + C{H_3}I$$
Answer :
$${C_2}{H_5}OH + C{H_3}I$$
$${C_2}{H_5}OC{H_3} + HI \to {C_2}{H_5}OH + C{H_3}I$$
33.
The compound which reacts fastest with Lucas reagent at room temperature is
A
$${\text{butan - 1 - ol}}$$
B
$${\text{butan - 2 - ol}}$$
C
$${\text{2 - methylpropan - 1 - ol}}$$
D
$${\text{2 - methylpropan - 2 - ol}}$$
Answer :
$${\text{2 - methylpropan - 2 - ol}}$$
TIPS/Formulae :
The order of reactivity of alcohol with Lucas reagent is $$tert. > sec. > pri.$$
Lucas test is based on the difference in the three types of alcohols ( having 6 or less carbon ) towads Lucas reagent (a mixture of conc. hydrochloric acid and anhydrous zinc chloride) at room temperature.
\[ROH+HCl\xrightarrow{ZnC{{l}_{2}}}RCl+{{H}_{2}}O\]
The tertiary alcohols produce turbidity immediately,
the secondary alcohols give turbidity within 5 - 10
minutes, and the primary alcohols do not give turbidity
at all, at room temperature.
Hence \[\text{2 - methylpropan - 2 - ol}\] ( a $${3^ \circ }$$ alcohol ) reacts fastest.
34.
Acid catalysed dehydration of $$t$$ - butanol is faster than that of $$n$$ - butanol because
A
tertiary carbocation is more stable than primary carbocation
B
primary carbocation is more stable than tertiary carbocation
C
$$t$$ - butanol has a higher boiling point
D
rearrangement takes place during dehydration of $$t$$ - butanol.
Answer :
tertiary carbocation is more stable than primary carbocation
No explanation is given for this question. Let's discuss the answer together.
35.
$$ortho$$ - Nitrophenol is less soluble in water than $$p$$ - and $$m$$ - nitrophenols because
A
$$o$$ - nitrophenol shows intramolecular $$H$$ - bonding
B
$$o$$ - nitrophenol shows intermolecular $$H$$ - bonding
C
melting point of $$o$$ - nitrophenol is lower than those of $$m$$ - and $$p$$ -isomers
D
$$o$$ - nitrophenol is more volatile in steam than those of $$m$$ - and $$p$$ -isomers
No explanation is given for this question. Let's discuss the answer together.
36.
A compound $$X\left( {{C_8}{H_{10}}O} \right)$$ upon treatment with alkaline solution of iodine gives a yellow precipitate. The filtrate on acidification gives a white solid $$Y\left( {{C_7}{H_6}{O_2}} \right).$$ Write the structures of $$X$$ and $$Y.$$
A
(a)
B
(b)
C
(c)
D
(d)
Answer :
(b)
Since the compound $$X\left( {{C_8}{H_{10}}O} \right)$$ gives haloform reaction ( i.e., forms iodoform on reaction with $${I_2} + NaOH$$ ), so it must contain either \[-\underset{\begin{smallmatrix}
\parallel \\
O
\end{smallmatrix}}{\mathop{C}}\,-C{{H}_{3}}\] or \[\underset{\begin{smallmatrix}
|\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
OH\,\,\,\,\,\,\,\,\,\,\,
\end{smallmatrix}}{\mathop{-CHC{{H}_{3}}}}\,\] group.
From the molecular formula of $$X$$ aromatic content of the compound is evident i.e., it contains a benzene ring
$${C_6}{H_5}CH\left( {OH} \right)C{H_3}$$ i.e.,
The given reactions are :
37.
The best reagent to convert pent-3-en-2-ol into pent-3-en-2-one is
A
acidic permanganate
B
acidic dichromate
C
chromic anhydride in glacial acetic acid
D
pyridinium chlorochromate
Answer :
pyridinium chlorochromate
Pyridinium chlorochromate oxidises an alcoholic group selectively in the presence of carbon-carbon double bond.
38.
Identify the nature of product in the following reaction \[+{{K}_{2}}{{S}_{2}}{{O}_{8}}\xrightarrow[{{H}_{2}}O]{H{{O}^{-}}}\text{Product}\]
A
B
C
D
Answer :
Oxidation of phenol by \[{{K}_{2}}{{S}_{2}}{{O}_{8}}\] is an example of $$Elbs$$ persulphate oxidation.
39.
In Williamson synthesis of mixed ether having a primary and a tertiary alkyl group if tertiary halide is used, then :
A
Rate of reaction will be slow due to slow cleavage of carbon-halogen bond.
B
Alkene will be the main product.
C
Simple ether will form instead of mixed ether.
D
Expected mixed ether will be formed.
Answer :
Alkene will be the main product.
The tertiary alkyl halide undergoes elimination reaction to give alkenes.
40.
Which of the following compounds does not react with $$NaOH?$$
A
$$C{H_3}COOH$$
B
$$C{H_3}CON{H_2}$$
C
$${C_6}{H_5}OH$$
D
$$C{H_3}C{H_2}OH$$
Answer :
$$C{H_3}C{H_2}OH$$
\[\begin{align}
& C{{H}_{3}}COOH\xrightarrow[-{{H}_{2}}O]{NaOH}C{{H}_{3}}COONa \\
& C{{H}_{3}}CON{{H}_{2}}\xrightarrow{NaOH}C{{H}_{3}}COONa+N{{H}_{3}} \\
& {{C}_{6}}{{H}_{5}}OH\xrightarrow{NaOH}{{C}_{6}}{{H}_{5}}ONa+{{H}_{2}}O \\
\end{align}\]
But alcohols are weakly acidic even weaker than water and react with alkali metals to form alkoxides and not with alkalies.