Alcohols Phenols and Ethers Test

Result

Alcohols Phenols and Ethers Test - 57

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Weekly Quiz Competition

Question 1
1 / -0

Primary alcohols on dehydration give

A
Alkenes

B
Alkanes

C
Both (a) and (b)

D
None of these

Solution

$$ \begin{matrix} R-CH_{ 2 }-CH_{ 2 }-OH \\ 1^{ 0 }\quad alcohol \end{matrix}\xrightarrow [ 170^{ 0 }C ]{ Conc.H_{ 2 }SO_{ 4 } } \begin{matrix} R-CH=CH_{ 2 }+H_{ 2 }O \\ Alkene \end{matrix} $$
Question 2
1 / -0

Which of the following reagents convert the propene to 1-propanol

A
$$ H_2O, H_2SO_4 $$

B
Aqueous KOH

C
$$ MhSO_4 , NaBH_4/ H_2 O $$

D
$$ B_2H_6, H_2O_2,OH^- $$

Solution

$$ \begin{matrix} CH_{ 3 }-CH=CH_{ 2 }+aq.KOH \\ Propene-1 \end{matrix}\rightarrow \begin{matrix} CH_{ 3 }-CH_{ 2 }-CH_{ 2 }OH \\ Propanol-1 \end{matrix} $$
Question 3
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Which of the following is most soluble in water?

A
n-butyl alcohol

B
Isobutyl alcohol

C
Tertiary butyl alcohol

D
Secondary butyl alcohol

Solution

The solubility of alcohols and phenols in water due to their ability to form hydrogen bonds with water molecules.
The solubility decreases with an increase in size of alkyl group which is a hydrophobic group, which makes the alcohol less hydrophilic.
In the case of isomers, the order of solubility in water is $$1^0>2^0>3^0$$ due to decrease in polar character.
Hence, among all, n-butyl alcohol is the most soluble in water.

The answer is option $$A$$.
Question 4
1 / -0

Directions For Questions

...view full instructions

The major product of (B) is:

A

B

C

D

Solution

Complete reaction can be illustrated as shown above.
Hence, Option "A" is the correct answer.
Question 5
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Which of the following is not characteristic of alcohols

A
They are lighter than water

B
Their boiling points rise fairly uniformly with increasing molecular weight

C
Lower members are insoluble in water and organic solvents but solubility regularly increases with molecular weight

D
Lower members have pleasant smell and burning taste, while higher members are odourless and tasteless

Solution

Lower members are soluble in water and solubility decreases with increasing molecular mass because the length of the hydrophobic chain increases.

Option C is correct.
Question 6
1 / -0

Dehydration of 2-butanol yields

A
1-butene

B
2-butene

C
2-butyne

D
both (A) and (B)

Solution
Question 7
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Which of the following alcohol does not give a stable compound on dehydration?

A
Ethyl alcohol

B
Methyl alcohol

C
n-propyl alcohol

D
n-butyl alcohol

Solution

Alcohols undergo dehydration (removal of water) to form an alkene.
To form alkene, we need at least two carbon atoms. But, methanol $$(CH_3OH)$$ has only one carbon atom. So, it does not give a stable compound on dehydration.

Hence, option $$B$$ is correct.
Question 8
1 / -0

Which compound is soluble in $$ H_2O $$

A
$$ HCHO $$

B
$$ CH_3CHO $$

C
$$ CH_3COCH_3 $$

D
All

Solution

$$\text{Reason: H-bonding}$$
Question 9
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Which of the following would undergo dehydration most readily?

A
1-phenyl-1butanol

B
2-phenyl-2-butanol

C
1-phenyl-2-butanol

D
2-phenyl-1-butanol

Solution

Dehydration of alcohols involves the formation of a carbocation intermediate.

Higher the stability of carbocation, higher is the ease of dehydration.
The order of stability of carbocation is $$Tertiary>Secondary>Primary$$

On dehydration, tertiary alcohol forms tertiary carbocation, secondary alcohol forms secondary alcohol, tertiary alcohol forms tertiary carbocation.
From the figure, we can see that only 2-phenyl-2-butanol is a tertiary phenol. So, it would undergo dehydration most readily.

Hence, option $$B$$ is correct.
Question 10
1 / -0

Which compound is soluble in water

A
$$ CS_2 $$

B
$$ C_2H_5OH $$

C
$$ CCl_4 $$

D
$$ CHCl_3 $$

Solution

$$ C_2H_5OH $$ is soluble in water due to H-bonding.