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CHXI11:THE P-BLOCK ELEMENTS

316087 Which of the following statements is false?

1

{BH}_{3}

is not a stable compound

2 All the

B - H

bonds in

B_{2} H_{6}

are equal

3 The boron hydrides are readily hydrolysed

4 Boron hydrides are prepared by the action of dil.

HCl

on

{Mg}_{3} B_{2}

.

Explanation:

All the $B - H$ bonds in $B_{2} H_{6}$ are not equal. The four terminal B-H bonds are shorter (B-H bond length $= 1 .19 \overset{o}{A}$ ) than the two bridged $BH - B$ bonds (bond length = $1 .33 \overset{o}{A}$

CHXI11:THE P-BLOCK ELEMENTS

316088 Identify the correct statement for $B_{2} H_{6}$ from those given below.
(A) In $B_{2} H_{6}$ , all B-H bonds are equivalent.
(B) In $B_{2} H_{6}$ there are four 3-centre-2-electron bonds.
(C) $B_{2} H_{6}$ is a Lewis acid.
(D) $B_{2} H_{6}$ can be synthesized from both ${BF}_{3}$ and ${NaBH}_{4}$ .
(E) $B_{2} H_{6}$ is a planar molecule.
Choose the most appropriate answer from the options given below :

1 (A) and (E) only

2 (B), (C) and (E) only

3 (C) and (D) only

4 (C) and (E) only

Explanation:

supporting img
(A), (B):
Two 3 centre -2 - electron bonds
(C) $B_{2} H_{6}$ is $e -$ deficient species
(E) $B_{2} H_{6}$ is non - Planar molecule
(D) ${BF}_{3} + {LiAlH}_{4} \to 2 B_{2} H_{6} + 3 LiF + 3 {AlF}_{3}$
${NaBH}_{4} + I_{2} \to B_{2} H_{6} + 2 NaI + H_{2}$

JEE - 2022

CHXI11:THE P-BLOCK ELEMENTS

316089 A compound $X$ , of boron reacts with ${NH}_{3}$ on heating to give another compound $Y$ which is called inroganic benzene. The compound X can be prepared by treating ${BF}_{3}$ with lithium aluminium hydride. The compounds $X$ and $Y$ are represented by the formulae

1

B_{2} H_{6}, B_{3} N_{3} H_{6}

2

B_{2} O_{3}, B_{3} N_{3} H_{6}

3

{BF}_{3}, B_{3} N_{3} H_{6}

4

B_{3} N_{3} H_{6}, B_{2} H_{6}

Explanation:

(i) $B_{2} H_{6} \cdot 2 {NH}_{3}$ which is formulated as ${[{BH}_{2} {({NH}_{3})}_{2}]}^{+} {[{BH}_{4}]}^{-}$ formed by the reaction of ammonia with diborane initially further on heating it changes into borazine, $B_{3} N_{3} H_{6}$
$\underset{(x)}{3 B_{2} H_{6}} + 6N H_{3} \overset{473 K}{\to} 2 \underset{(y)}{B_{3} N_{3} N_{6}} + 12 H_{2}$
Borazole has cyclic structure and is isoelectronic and isosteric with benzene and thus called inorganic benzene.
ii) By the reduction of ${BF}_{3}$ with lithium aluminium hydride in diethyl ether diborane can be prepared.
$4 {BF}_{3} + 3 {LiAlH}_{4} \to 2 B_{2} H_{6} + 3 {AlF}_{3} + 3 LiF$

CHXI11:THE P-BLOCK ELEMENTS

316090 Orthoboric acid $(H_{3} {BO}_{3})$ and metaboric acid $({HBO}_{2})$ differ in respect of

1 Basicity

2 Structure

3 Melting point

4 All of these

Explanation:

$H_{3} {BO}_{3}$ is dibasic acid and ${HBO}_{2}$ is monobasic acid. $H_{3} {BO}_{3}$ structure is
supporting img
and trimer of ${HBO}_{2}$ is

$H_{3} {BO}_{3}$ melting point is $170 {.9}^{\circ} C$
${HBO}_{2}$ melting point is $170^{\circ} C$

CHXI11:THE P-BLOCK ELEMENTS

316087 Which of the following statements is false?

1

{BH}_{3}

is not a stable compound

2 All the

B - H

bonds in

B_{2} H_{6}

are equal

3 The boron hydrides are readily hydrolysed

4 Boron hydrides are prepared by the action of dil.

HCl

on

{Mg}_{3} B_{2}

.

Explanation:

All the $B - H$ bonds in $B_{2} H_{6}$ are not equal. The four terminal B-H bonds are shorter (B-H bond length $= 1 .19 \overset{o}{A}$ ) than the two bridged $BH - B$ bonds (bond length = $1 .33 \overset{o}{A}$

CHXI11:THE P-BLOCK ELEMENTS

316088 Identify the correct statement for $B_{2} H_{6}$ from those given below.
(A) In $B_{2} H_{6}$ , all B-H bonds are equivalent.
(B) In $B_{2} H_{6}$ there are four 3-centre-2-electron bonds.
(C) $B_{2} H_{6}$ is a Lewis acid.
(D) $B_{2} H_{6}$ can be synthesized from both ${BF}_{3}$ and ${NaBH}_{4}$ .
(E) $B_{2} H_{6}$ is a planar molecule.
Choose the most appropriate answer from the options given below :

1 (A) and (E) only

2 (B), (C) and (E) only

3 (C) and (D) only

4 (C) and (E) only

Explanation:

supporting img
(A), (B):
Two 3 centre -2 - electron bonds
(C) $B_{2} H_{6}$ is $e -$ deficient species
(E) $B_{2} H_{6}$ is non - Planar molecule
(D) ${BF}_{3} + {LiAlH}_{4} \to 2 B_{2} H_{6} + 3 LiF + 3 {AlF}_{3}$
${NaBH}_{4} + I_{2} \to B_{2} H_{6} + 2 NaI + H_{2}$

JEE - 2022

CHXI11:THE P-BLOCK ELEMENTS

316089 A compound $X$ , of boron reacts with ${NH}_{3}$ on heating to give another compound $Y$ which is called inroganic benzene. The compound X can be prepared by treating ${BF}_{3}$ with lithium aluminium hydride. The compounds $X$ and $Y$ are represented by the formulae

1

B_{2} H_{6}, B_{3} N_{3} H_{6}

2

B_{2} O_{3}, B_{3} N_{3} H_{6}

3

{BF}_{3}, B_{3} N_{3} H_{6}

4

B_{3} N_{3} H_{6}, B_{2} H_{6}

Explanation:

(i) $B_{2} H_{6} \cdot 2 {NH}_{3}$ which is formulated as ${[{BH}_{2} {({NH}_{3})}_{2}]}^{+} {[{BH}_{4}]}^{-}$ formed by the reaction of ammonia with diborane initially further on heating it changes into borazine, $B_{3} N_{3} H_{6}$
$\underset{(x)}{3 B_{2} H_{6}} + 6N H_{3} \overset{473 K}{\to} 2 \underset{(y)}{B_{3} N_{3} N_{6}} + 12 H_{2}$
Borazole has cyclic structure and is isoelectronic and isosteric with benzene and thus called inorganic benzene.
ii) By the reduction of ${BF}_{3}$ with lithium aluminium hydride in diethyl ether diborane can be prepared.
$4 {BF}_{3} + 3 {LiAlH}_{4} \to 2 B_{2} H_{6} + 3 {AlF}_{3} + 3 LiF$

CHXI11:THE P-BLOCK ELEMENTS

316090 Orthoboric acid $(H_{3} {BO}_{3})$ and metaboric acid $({HBO}_{2})$ differ in respect of

1 Basicity

2 Structure

3 Melting point

4 All of these

Explanation:

$H_{3} {BO}_{3}$ is dibasic acid and ${HBO}_{2}$ is monobasic acid. $H_{3} {BO}_{3}$ structure is
supporting img
and trimer of ${HBO}_{2}$ is

$H_{3} {BO}_{3}$ melting point is $170 {.9}^{\circ} C$
${HBO}_{2}$ melting point is $170^{\circ} C$

CHXI11:THE P-BLOCK ELEMENTS

316087 Which of the following statements is false?

1

{BH}_{3}

is not a stable compound

2 All the

B - H

bonds in

B_{2} H_{6}

are equal

3 The boron hydrides are readily hydrolysed

4 Boron hydrides are prepared by the action of dil.

HCl

on

{Mg}_{3} B_{2}

.

Explanation:

All the $B - H$ bonds in $B_{2} H_{6}$ are not equal. The four terminal B-H bonds are shorter (B-H bond length $= 1 .19 \overset{o}{A}$ ) than the two bridged $BH - B$ bonds (bond length = $1 .33 \overset{o}{A}$

CHXI11:THE P-BLOCK ELEMENTS

316088 Identify the correct statement for $B_{2} H_{6}$ from those given below.
(A) In $B_{2} H_{6}$ , all B-H bonds are equivalent.
(B) In $B_{2} H_{6}$ there are four 3-centre-2-electron bonds.
(C) $B_{2} H_{6}$ is a Lewis acid.
(D) $B_{2} H_{6}$ can be synthesized from both ${BF}_{3}$ and ${NaBH}_{4}$ .
(E) $B_{2} H_{6}$ is a planar molecule.
Choose the most appropriate answer from the options given below :

1 (A) and (E) only

2 (B), (C) and (E) only

3 (C) and (D) only

4 (C) and (E) only

Explanation:

supporting img
(A), (B):
Two 3 centre -2 - electron bonds
(C) $B_{2} H_{6}$ is $e -$ deficient species
(E) $B_{2} H_{6}$ is non - Planar molecule
(D) ${BF}_{3} + {LiAlH}_{4} \to 2 B_{2} H_{6} + 3 LiF + 3 {AlF}_{3}$
${NaBH}_{4} + I_{2} \to B_{2} H_{6} + 2 NaI + H_{2}$

JEE - 2022

CHXI11:THE P-BLOCK ELEMENTS

316089 A compound $X$ , of boron reacts with ${NH}_{3}$ on heating to give another compound $Y$ which is called inroganic benzene. The compound X can be prepared by treating ${BF}_{3}$ with lithium aluminium hydride. The compounds $X$ and $Y$ are represented by the formulae

1

B_{2} H_{6}, B_{3} N_{3} H_{6}

2

B_{2} O_{3}, B_{3} N_{3} H_{6}

3

{BF}_{3}, B_{3} N_{3} H_{6}

4

B_{3} N_{3} H_{6}, B_{2} H_{6}

Explanation:

(i) $B_{2} H_{6} \cdot 2 {NH}_{3}$ which is formulated as ${[{BH}_{2} {({NH}_{3})}_{2}]}^{+} {[{BH}_{4}]}^{-}$ formed by the reaction of ammonia with diborane initially further on heating it changes into borazine, $B_{3} N_{3} H_{6}$
$\underset{(x)}{3 B_{2} H_{6}} + 6N H_{3} \overset{473 K}{\to} 2 \underset{(y)}{B_{3} N_{3} N_{6}} + 12 H_{2}$
Borazole has cyclic structure and is isoelectronic and isosteric with benzene and thus called inorganic benzene.
ii) By the reduction of ${BF}_{3}$ with lithium aluminium hydride in diethyl ether diborane can be prepared.
$4 {BF}_{3} + 3 {LiAlH}_{4} \to 2 B_{2} H_{6} + 3 {AlF}_{3} + 3 LiF$

CHXI11:THE P-BLOCK ELEMENTS

316090 Orthoboric acid $(H_{3} {BO}_{3})$ and metaboric acid $({HBO}_{2})$ differ in respect of

1 Basicity

2 Structure

3 Melting point

4 All of these

Explanation:

$H_{3} {BO}_{3}$ is dibasic acid and ${HBO}_{2}$ is monobasic acid. $H_{3} {BO}_{3}$ structure is
supporting img
and trimer of ${HBO}_{2}$ is

$H_{3} {BO}_{3}$ melting point is $170 {.9}^{\circ} C$
${HBO}_{2}$ melting point is $170^{\circ} C$

CHXI11:THE P-BLOCK ELEMENTS

316087 Which of the following statements is false?

1

{BH}_{3}

is not a stable compound

2 All the

B - H

bonds in

B_{2} H_{6}

are equal

3 The boron hydrides are readily hydrolysed

4 Boron hydrides are prepared by the action of dil.

HCl

on

{Mg}_{3} B_{2}

.

Explanation:

All the $B - H$ bonds in $B_{2} H_{6}$ are not equal. The four terminal B-H bonds are shorter (B-H bond length $= 1 .19 \overset{o}{A}$ ) than the two bridged $BH - B$ bonds (bond length = $1 .33 \overset{o}{A}$

CHXI11:THE P-BLOCK ELEMENTS

316088 Identify the correct statement for $B_{2} H_{6}$ from those given below.
(A) In $B_{2} H_{6}$ , all B-H bonds are equivalent.
(B) In $B_{2} H_{6}$ there are four 3-centre-2-electron bonds.
(C) $B_{2} H_{6}$ is a Lewis acid.
(D) $B_{2} H_{6}$ can be synthesized from both ${BF}_{3}$ and ${NaBH}_{4}$ .
(E) $B_{2} H_{6}$ is a planar molecule.
Choose the most appropriate answer from the options given below :

1 (A) and (E) only

2 (B), (C) and (E) only

3 (C) and (D) only

4 (C) and (E) only

Explanation:

supporting img
(A), (B):
Two 3 centre -2 - electron bonds
(C) $B_{2} H_{6}$ is $e -$ deficient species
(E) $B_{2} H_{6}$ is non - Planar molecule
(D) ${BF}_{3} + {LiAlH}_{4} \to 2 B_{2} H_{6} + 3 LiF + 3 {AlF}_{3}$
${NaBH}_{4} + I_{2} \to B_{2} H_{6} + 2 NaI + H_{2}$

JEE - 2022

CHXI11:THE P-BLOCK ELEMENTS

316089 A compound $X$ , of boron reacts with ${NH}_{3}$ on heating to give another compound $Y$ which is called inroganic benzene. The compound X can be prepared by treating ${BF}_{3}$ with lithium aluminium hydride. The compounds $X$ and $Y$ are represented by the formulae

1

B_{2} H_{6}, B_{3} N_{3} H_{6}

2

B_{2} O_{3}, B_{3} N_{3} H_{6}

3

{BF}_{3}, B_{3} N_{3} H_{6}

4

B_{3} N_{3} H_{6}, B_{2} H_{6}

Explanation:

(i) $B_{2} H_{6} \cdot 2 {NH}_{3}$ which is formulated as ${[{BH}_{2} {({NH}_{3})}_{2}]}^{+} {[{BH}_{4}]}^{-}$ formed by the reaction of ammonia with diborane initially further on heating it changes into borazine, $B_{3} N_{3} H_{6}$
$\underset{(x)}{3 B_{2} H_{6}} + 6N H_{3} \overset{473 K}{\to} 2 \underset{(y)}{B_{3} N_{3} N_{6}} + 12 H_{2}$
Borazole has cyclic structure and is isoelectronic and isosteric with benzene and thus called inorganic benzene.
ii) By the reduction of ${BF}_{3}$ with lithium aluminium hydride in diethyl ether diborane can be prepared.
$4 {BF}_{3} + 3 {LiAlH}_{4} \to 2 B_{2} H_{6} + 3 {AlF}_{3} + 3 LiF$

CHXI11:THE P-BLOCK ELEMENTS

316090 Orthoboric acid $(H_{3} {BO}_{3})$ and metaboric acid $({HBO}_{2})$ differ in respect of

1 Basicity

2 Structure

3 Melting point

4 All of these

Explanation:

$H_{3} {BO}_{3}$ is dibasic acid and ${HBO}_{2}$ is monobasic acid. $H_{3} {BO}_{3}$ structure is
supporting img
and trimer of ${HBO}_{2}$ is

$H_{3} {BO}_{3}$ melting point is $170 {.9}^{\circ} C$
${HBO}_{2}$ melting point is $170^{\circ} C$

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