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CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323201 Consider the following reaction
supporting img
In the above reaction, ester formation takes place by:

1 Breaking of

O - H

bond of

(A)

and

O - H

bond of (B)

2 Breaking of

C - O

bond of (A) and

C - O

bond of (B)

3 Breaking of

O - H

bond of

(A)

and

C - O

bond of (B)

4 Breaking of

C - O

bond of (A) and

O - H

bond of (B)

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323202 $0.037 g$ of an alcohol, $R - OH$ was added to ${CH}_{3} MgBr$ and the gas evolved measured 11.2 $mL$ at STP. The molecular mass of $R - OH$ will be

1 47

2 79

3 74

4 77

Explanation:

$\underset{1 m o l}{R - O H} + C H_{3} M g B r \to \underset{\binom{1 m o l}{\binom{o r}{22400 m L a t S T P}}}{C H_{4}} + M g (B r) O R$
$11.2 mL C H_{4}$ at STP is formed from
$0.037 g$ $ROH$ .
$∴ 22400 mL C H_{4}$ at STP will be formed from $\frac{0 .037}{11 .2} \times 22400 g ROH = 74 g ROH$
$∴$ Molecular mass of $ROH = 74$

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323203 An organic compound ' $A$ ' containing $C, H$ and $O$ has a pleasant odour with boiling point $78^{\circ} C$ . On boiling 'A' with conc $H_{2} {SO}_{4}$ , a colourless gas is released. The organic liquid ' $A$ ' is :

1

C_{2} H_{5} Cl

2

C_{2} H_{5} {COOCH}_{3}

3

C_{2} H_{5} OH

4

C_{2} H_{6}

Explanation:

$C_{2} H_{5} OH$ has pleasant odour with boiling point $78^{\circ} C$ .

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323204 Assertion :
An alcohol does not react with halide ions as such but on dissolution in strong acids it does react smoothly forming an alkyl halide.
Reason :
The strong acid accelerates the removal of proton from the -OH group of the alcohol.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

Protonation of the $- OH$ group by strong acids converts it into a better leaving group, crucial for facilitating nucleophilic substitution reactions by forming a stable water molecule as the leaving group. So the option (3) is correct.

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323201 Consider the following reaction
supporting img
In the above reaction, ester formation takes place by:

1 Breaking of

O - H

bond of

(A)

and

O - H

bond of (B)

2 Breaking of

C - O

bond of (A) and

C - O

bond of (B)

3 Breaking of

O - H

bond of

(A)

and

C - O

bond of (B)

4 Breaking of

C - O

bond of (A) and

O - H

bond of (B)

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323202 $0.037 g$ of an alcohol, $R - OH$ was added to ${CH}_{3} MgBr$ and the gas evolved measured 11.2 $mL$ at STP. The molecular mass of $R - OH$ will be

1 47

2 79

3 74

4 77

Explanation:

$\underset{1 m o l}{R - O H} + C H_{3} M g B r \to \underset{\binom{1 m o l}{\binom{o r}{22400 m L a t S T P}}}{C H_{4}} + M g (B r) O R$
$11.2 mL C H_{4}$ at STP is formed from
$0.037 g$ $ROH$ .
$∴ 22400 mL C H_{4}$ at STP will be formed from $\frac{0 .037}{11 .2} \times 22400 g ROH = 74 g ROH$
$∴$ Molecular mass of $ROH = 74$

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323203 An organic compound ' $A$ ' containing $C, H$ and $O$ has a pleasant odour with boiling point $78^{\circ} C$ . On boiling 'A' with conc $H_{2} {SO}_{4}$ , a colourless gas is released. The organic liquid ' $A$ ' is :

1

C_{2} H_{5} Cl

2

C_{2} H_{5} {COOCH}_{3}

3

C_{2} H_{5} OH

4

C_{2} H_{6}

Explanation:

$C_{2} H_{5} OH$ has pleasant odour with boiling point $78^{\circ} C$ .

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323204 Assertion :
An alcohol does not react with halide ions as such but on dissolution in strong acids it does react smoothly forming an alkyl halide.
Reason :
The strong acid accelerates the removal of proton from the -OH group of the alcohol.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

Protonation of the $- OH$ group by strong acids converts it into a better leaving group, crucial for facilitating nucleophilic substitution reactions by forming a stable water molecule as the leaving group. So the option (3) is correct.

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323201 Consider the following reaction
supporting img
In the above reaction, ester formation takes place by:

1 Breaking of

O - H

bond of

(A)

and

O - H

bond of (B)

2 Breaking of

C - O

bond of (A) and

C - O

bond of (B)

3 Breaking of

O - H

bond of

(A)

and

C - O

bond of (B)

4 Breaking of

C - O

bond of (A) and

O - H

bond of (B)

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323202 $0.037 g$ of an alcohol, $R - OH$ was added to ${CH}_{3} MgBr$ and the gas evolved measured 11.2 $mL$ at STP. The molecular mass of $R - OH$ will be

1 47

2 79

3 74

4 77

Explanation:

$\underset{1 m o l}{R - O H} + C H_{3} M g B r \to \underset{\binom{1 m o l}{\binom{o r}{22400 m L a t S T P}}}{C H_{4}} + M g (B r) O R$
$11.2 mL C H_{4}$ at STP is formed from
$0.037 g$ $ROH$ .
$∴ 22400 mL C H_{4}$ at STP will be formed from $\frac{0 .037}{11 .2} \times 22400 g ROH = 74 g ROH$
$∴$ Molecular mass of $ROH = 74$

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323203 An organic compound ' $A$ ' containing $C, H$ and $O$ has a pleasant odour with boiling point $78^{\circ} C$ . On boiling 'A' with conc $H_{2} {SO}_{4}$ , a colourless gas is released. The organic liquid ' $A$ ' is :

1

C_{2} H_{5} Cl

2

C_{2} H_{5} {COOCH}_{3}

3

C_{2} H_{5} OH

4

C_{2} H_{6}

Explanation:

$C_{2} H_{5} OH$ has pleasant odour with boiling point $78^{\circ} C$ .

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323204 Assertion :
An alcohol does not react with halide ions as such but on dissolution in strong acids it does react smoothly forming an alkyl halide.
Reason :
The strong acid accelerates the removal of proton from the -OH group of the alcohol.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

Protonation of the $- OH$ group by strong acids converts it into a better leaving group, crucial for facilitating nucleophilic substitution reactions by forming a stable water molecule as the leaving group. So the option (3) is correct.

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323201 Consider the following reaction
supporting img
In the above reaction, ester formation takes place by:

1 Breaking of

O - H

bond of

(A)

and

O - H

bond of (B)

2 Breaking of

C - O

bond of (A) and

C - O

bond of (B)

3 Breaking of

O - H

bond of

(A)

and

C - O

bond of (B)

4 Breaking of

C - O

bond of (A) and

O - H

bond of (B)

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323202 $0.037 g$ of an alcohol, $R - OH$ was added to ${CH}_{3} MgBr$ and the gas evolved measured 11.2 $mL$ at STP. The molecular mass of $R - OH$ will be

1 47

2 79

3 74

4 77

Explanation:

$\underset{1 m o l}{R - O H} + C H_{3} M g B r \to \underset{\binom{1 m o l}{\binom{o r}{22400 m L a t S T P}}}{C H_{4}} + M g (B r) O R$
$11.2 mL C H_{4}$ at STP is formed from
$0.037 g$ $ROH$ .
$∴ 22400 mL C H_{4}$ at STP will be formed from $\frac{0 .037}{11 .2} \times 22400 g ROH = 74 g ROH$
$∴$ Molecular mass of $ROH = 74$

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323203 An organic compound ' $A$ ' containing $C, H$ and $O$ has a pleasant odour with boiling point $78^{\circ} C$ . On boiling 'A' with conc $H_{2} {SO}_{4}$ , a colourless gas is released. The organic liquid ' $A$ ' is :

1

C_{2} H_{5} Cl

2

C_{2} H_{5} {COOCH}_{3}

3

C_{2} H_{5} OH

4

C_{2} H_{6}

Explanation:

$C_{2} H_{5} OH$ has pleasant odour with boiling point $78^{\circ} C$ .

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323204 Assertion :
An alcohol does not react with halide ions as such but on dissolution in strong acids it does react smoothly forming an alkyl halide.
Reason :
The strong acid accelerates the removal of proton from the -OH group of the alcohol.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

Protonation of the $- OH$ group by strong acids converts it into a better leaving group, crucial for facilitating nucleophilic substitution reactions by forming a stable water molecule as the leaving group. So the option (3) is correct.

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