CBSE 12th Standard Chemistry Alcohols , Phenols and Ethers HOT Questions Study Material - QB365 Set A | QB365

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CBSE 12th Standard Chemistry Alcohols , Phenols and Ethers HOT Questions Study Material - QB365 Set A

Published on: 02/11/2025

Question Set A

CBSE 12th Standard Chemistry Alcohols , Phenols and Ethers HOT Questions Study Material - QB365

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Std: 12th Standard CBSE - Chemistry

chapter: Alcohols , Phenols and Ethers - HOT Questions

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Questions:

Generic 2

9 x 2 = 18

Describe the chemical test to distinguish between ethanol and phenol.

Write the equation involved in the acetylation of salicylic acid.

What is the main product obtained when vapors of t-butyl alcohol are passed over copper at 300⁰C?

Write IUPAC name of the following:
\({ CH }_{ 3 }-\underset { \overset { | }{ { CH }_{ 3 } } }{ C } =\underset { \overset { | }{ { Br } } }{ C } -{ CH }_{ 2 }OH\)

Write steps to carry out the conversion of phenol to aspirin.

Give the equations of reactions of preparation of phenol from cumene

What is meant by hydroboration-oxidation reaction? Illustrate with an example.

Write the equations involved in the
Reimenn-Tiemann reaction.

Out of 2-chloroethanol and ethanol, which one is more acidic and why?

Multiple Choice Question

10 x 1 = 10

10.

Which of the following alcohols will not undergo oxidation?

(a)

Butanol

(b)

Butan-2-ol

(c)

2-methylbutan-2-ol

(d)

3-methylbutan-2-ol

11.

Lucas reagent produces cloudiness immediately with

(a)

(b)

(c)

CH₃ - CH₂ - CH₂ - OH

(d)

12.

Salicylic acid on heating with acetic anhydride in basic medium gives

(a)

Aspirin

(b)

Methyl salicylate

(c)

Phenyl salicylate

(d)

Acetyl salicylate

13.

The electrophile used in Reimer-Tiemann reaction is

(a)

\(\begin{equation} \mathrm{CCl}_{3}^{\oplus} \end{equation}\)

(b)

CCI₂

(c)

\(\begin{equation} \mathrm{Cl}_{3}^{\oplus} \end{equation}\)

(d)

H₂O

14.

The correct order of decreasing acidity of nitrophenols will be

(a)

m-nitrophenol > p-nitrophenol > o-nitrophenol

(b)

o-nitrophenol > m-nitrophenol > p-nitrophenol

(c)

p-nitrophenol > m-nitrophenol > o-nitrophenol

(d)

p-nitrophenol > o-nitrophenol > m-nitrophenol

15.

Isopropyl benzene is oxidised in the presence of air to compound 'A'. When compound 'A' is treated with dilute mineral acid,the aromatic product formed is

(a)

phenol

(b)

benzene

(c)

benzaldehyde

(d)

acetophenone

(e)

toluene

16.

The most suitable reagent for the conversion of R-CH₂OH \(\longrightarrow\) R-CHO is

(a)

PCC(Pyridinium chlorochromate)

(b)

KMnO₄

(c)

CrO₃

(d)

K₂Cr₂O₇

17.

Propene on hydroboration-oxidation produces

(a)

CH₃CH₂CH₂OH

(b)

CH₃CHOHCH₃

(c)

CH₃CHOHCH₂OH

(d)

CH₃CH₂CHO

18.

What is the correct order of reactivity of alcohols in the following reaction?
\(R-OH+HCI\overset { ZnCl_{ 2 } }{ \longrightarrow } R-Cl+{ H }_{ 2 }O\)

(a)

\({ 1 }^{ \circ }>{ 2 }^{ \circ }>{ 3 }^{ \circ }\)

(b)

\({ 1 }^{ \circ }<{ 2 }^{ \circ }{ >3 }^{ \circ }\)

(c)

\({ 3 }^{ \circ }>{ 2 }^{ \circ }>{ 1 }^{ \circ }\)

(d)

\({ 3 }^{ \circ }>{ 1 }^{ \circ }>{ 2 }^{ \circ }\)

19.

The compound (C) in the following series of reactions is:
\(Aceton+{ CH }_{ 3 }MgBr\overset { Dry\ ether }{ \longrightarrow } A\overset { { H }_{ 3 }{ O }^{ + } }{ \longrightarrow } B\overset { 363K }{ \underset { 20%{ H }_{ 2 }{ SO }_{ 4 } }{ \longrightarrow } } C+H_{ 2 }O\)

(a)

2-Methylpropene

(b)

but-2-ene

(c)

but-1-ene

(d)

propene

Generic 5

4 x 5 = 20

20.

(i) How is phenol obtained from (a) aniline (b) benzene sulphonic acid?
(ii) How it can be converted into (a) salicylaldehyde (b) benzoquinone (c) toluene?

21.

Write chemical reaction for the preparation of phenol from chlorobenzene.

22.

Write structures of the compounds whose IUPAC names are as follows:
(i) 2-Methylbutan-2-ol
(ii) 1-Phenylpropan-2-ol
(iii) 3,5-Dimethylhexane –1, 3, 5-triol
(iv) 2,3 – Diethylphenol
(v) 1 – Ethoxypropane
(vi) 2-Ethoxy-3-methylpentane
(vii) Cyclohexylmethanol
(viii) 3-Cyclohexylpentan-3-ol
(ix) Cyclopent-3-en-1-ol
(x) 4-Chloro-3-ethylbutan-1-ol.

23.

Write equation of the following reactions.
(i) Friedel-Crafts reaction (alkylation in anisole)
(ii) Nitration of anisole
(iii) Bromination of anisole in ethanoic acid medium
(iv) Friedel-Crafts (acetylation of anisole)

Generic 3

1 x 3 = 3

24.

How does Lucas reagent help in the distinction of primary, secondary and tertiary alcohols? Discuss the reactions involved.

Case Study Questions

1 x 4 = 4

25.

Read the passage given below and answer the following questions:
Reimer- Tiemann reaction introduces an aldehyde group, on aromatic ring of phenol, ortho to the hydroxyl group. This is a general method for the synthesis of substituted salicylaldehydes as depicted below.
The following questions are multiple choice questions. Choose the most appropriate answer:
(i) Reimer-Tiemann reaction is an example of

(a) nucleophilic substitution reaction	(b) electrophilic substitution reaction
(c) nucleophilic addition reaction	(d) electrophilic addition reaction

(ii) Which of the following reagents is used in the given reaction in steps I?

(a) aq. NaOH + CH₃CI

(b) aq. NaOH + CH₂Cl₂

(c) aq. NaOH + CHCl₃

(d) aq. NaOH + CCl₄

(iii) The structure of the intermediate [A] is

(iv) When phenol reacts with chloroform in presence of KOH, the product formed is

(a) salicylic acid

(b) salicylaldehyde

(c) both (a) and (b)

(d) none of these.

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Answers Key:

Generic 2

9 x 2 = 18

Ethanol when warmed with NaOH + I₂ gives yellow ppt of iodoform while phenol does not give this test.

Isobutylene (2-Methyl propane)

2-Bromo-3-methyl but-2-en-1-ol

The addition of diborane to alkenes to form trialkylboranes followed by their oxidation with alkaline hydrogen peroxide to form alcohols is called hydroboration-oxidation reaction.

For example,
\(\underset { Propene }{ { CH }_{ 3 }CH={ CH }_{ 2 } } \overset { { BH }_{ 3 } }{ \underset { THF }{ \longrightarrow } } ({ CH }_{ 3 }{ CH }_{ 2 }{ CH }_{ 2 })\overset { { OH }^{ - },{ H }_{ 2 }{ O }_{ 2 } }{ \longrightarrow } \underset { Propene-1-ol }{ { 3CH }_{ 3 }CH{ CH }_{ 2 } } OH+B({ OH })_{ 3 }\)

2-chloroethanol is more acidic than ethanol. Due to -I-effect (electron withdrawing group)of the CI-atom, electron density on O-H bond decreases. So, O-H bond of 2-chloroethanol becomes weaker than O-H bond of ethanol. Thus, the release of H⁺ ion from O-H bond of 2-chloroethane becomes easier.

Multiple Choice Question

10 x 1 = 10

10.

11.

12.

(a)
Aspirin

13.

(b)
CCI₂

14.

(d)
p-nitrophenol > o-nitrophenol > m-nitrophenol

15.

(a)
phenol

16.

(a)
PCC(Pyridinium chlorochromate)

17.

(a)
CH₃CH₂CH₂OH

18.

19.

(a)
2-Methylpropene

Generic 5

4 x 5 = 20

20.

21.

Chlorobenzene is fused with NaOH (at 623 K and 320 atm pressure) to produce sodium phenoxide, which gives phenol on acidification.

22.

(i)

(ii)

(iii)

(iv)

(v)
\(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{O}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{3}\)
(vi)

(vii)

(viii)

(ix)

(x)

23.

Generic 3

1 x 3 = 3

24.

The Lucas test differentiates between primary, secondary, and tertiary alcohols.
It is based on the difference in reactivity of the alcohols with HCl in an S_N1 reaction:
ROH + HCl→RCl+H₂O
It works because secondary carbocations are more stable and form faster than primary carbocations, and tertiary carbocations are so stable that the reaction takes place almost immediately.

Case Study Questions

1 x 4 = 4

25.

(i) (b): It is an electrophilic substitution reaction.
(ii) (c)

(iv) (b): It is known as Reimer-Tiemann reaction.