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CHXI11:THE P-BLOCK ELEMENTS

316214 Assertion :
Anhydrous ${AlCl}_{3}$ is covalent but hydrated ${AlCl}_{3}$ is ionic.
Reason :
In water, ${Al}_{2} {Cl}_{6}$ dissociates into hydrated ${Al}^{3 +}$ and ${Cl}^{-}$ ions due to high heat of hydration of these ions.

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:

When anhydrous ${AlCl}_{3}$ is dissolved in water, it changes to hydrated ${AlCl}_{3}$ , which is ionic in nature. The dimeric formula is retained in a non-polar solvent but is broken into ${Al}^{+ 3}$ and ${Cl}^{- 1}$ ions upon dissolution in water, due to the high heat of hydration. So, option (1) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316215 Which one of the following elements is unable to form ${MF}_{6}^{3 -}$ ion?

1

B

2

In

3

Al

4

Ga

Explanation:

Due to non-availability of vacant ' $d$ ' orbital.

NEET - 2018

CHXI11:THE P-BLOCK ELEMENTS

316233 Assertion :
Although ${PF}_{5}, {PCl}_{5}$ and ${PBr}_{5}$ are known, the pentahalides of nitrogen have not been observed.
Reason :
Phosphorus has lower electronegativity than nitrogen

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:

Nitrogen does not have d orbitals, due to which it cannot have covalency beyond four. Therefore it cannot form pentahalides. Electronegativity of ' $N$ ' is more than ' $P$ '. But it is not the reason for given assertion. So option (2) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316216 The Lewis acid character of boron trihalides follows the order

1

{BF}_{3} > {BCl}_{3} > {BBr}_{3} > {BI}_{3}

2

{BI}_{3} > {BBr}_{3} > {BCl}_{3} > {BF}_{3}

3

{BBr}_{3} > {BI}_{3} > {BCl}_{3} > {BF}_{3}

4

{BCl}_{3} > {BF}_{3} > {BBr}_{3} > {BI}_{3}

Explanation:

Extent of back bonding reduces down the group leading to more Lewis acidic strength.
${BF}_{3} > {BCl}_{3} > {BBr}_{3} > {BI}_{3}$ (Extent of back bonding)
( $2 p - 2 p) (2 p - 3 p) (2 p - 4 p) (2 p - 5 p)$
So, ${BF}_{3} < {BCl}_{3} < {BBr}_{3} < {BI}_{3}$ (Lewis acidic nature).
On the basis of small bonding smaller be the halide atom, more effective the back bonding & shows less tendency to accept a pair of electrons.

JEE - 2023

CHXI11:THE P-BLOCK ELEMENTS

316214 Assertion :
Anhydrous ${AlCl}_{3}$ is covalent but hydrated ${AlCl}_{3}$ is ionic.
Reason :
In water, ${Al}_{2} {Cl}_{6}$ dissociates into hydrated ${Al}^{3 +}$ and ${Cl}^{-}$ ions due to high heat of hydration of these ions.

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:

When anhydrous ${AlCl}_{3}$ is dissolved in water, it changes to hydrated ${AlCl}_{3}$ , which is ionic in nature. The dimeric formula is retained in a non-polar solvent but is broken into ${Al}^{+ 3}$ and ${Cl}^{- 1}$ ions upon dissolution in water, due to the high heat of hydration. So, option (1) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316215 Which one of the following elements is unable to form ${MF}_{6}^{3 -}$ ion?

1

B

2

In

3

Al

4

Ga

Explanation:

Due to non-availability of vacant ' $d$ ' orbital.

NEET - 2018

CHXI11:THE P-BLOCK ELEMENTS

316233 Assertion :
Although ${PF}_{5}, {PCl}_{5}$ and ${PBr}_{5}$ are known, the pentahalides of nitrogen have not been observed.
Reason :
Phosphorus has lower electronegativity than nitrogen

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:

Nitrogen does not have d orbitals, due to which it cannot have covalency beyond four. Therefore it cannot form pentahalides. Electronegativity of ' $N$ ' is more than ' $P$ '. But it is not the reason for given assertion. So option (2) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316216 The Lewis acid character of boron trihalides follows the order

1

{BF}_{3} > {BCl}_{3} > {BBr}_{3} > {BI}_{3}

2

{BI}_{3} > {BBr}_{3} > {BCl}_{3} > {BF}_{3}

3

{BBr}_{3} > {BI}_{3} > {BCl}_{3} > {BF}_{3}

4

{BCl}_{3} > {BF}_{3} > {BBr}_{3} > {BI}_{3}

Explanation:

Extent of back bonding reduces down the group leading to more Lewis acidic strength.
${BF}_{3} > {BCl}_{3} > {BBr}_{3} > {BI}_{3}$ (Extent of back bonding)
( $2 p - 2 p) (2 p - 3 p) (2 p - 4 p) (2 p - 5 p)$
So, ${BF}_{3} < {BCl}_{3} < {BBr}_{3} < {BI}_{3}$ (Lewis acidic nature).
On the basis of small bonding smaller be the halide atom, more effective the back bonding & shows less tendency to accept a pair of electrons.

JEE - 2023

CHXI11:THE P-BLOCK ELEMENTS

316214 Assertion :
Anhydrous ${AlCl}_{3}$ is covalent but hydrated ${AlCl}_{3}$ is ionic.
Reason :
In water, ${Al}_{2} {Cl}_{6}$ dissociates into hydrated ${Al}^{3 +}$ and ${Cl}^{-}$ ions due to high heat of hydration of these ions.

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:

When anhydrous ${AlCl}_{3}$ is dissolved in water, it changes to hydrated ${AlCl}_{3}$ , which is ionic in nature. The dimeric formula is retained in a non-polar solvent but is broken into ${Al}^{+ 3}$ and ${Cl}^{- 1}$ ions upon dissolution in water, due to the high heat of hydration. So, option (1) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316215 Which one of the following elements is unable to form ${MF}_{6}^{3 -}$ ion?

1

B

2

In

3

Al

4

Ga

Explanation:

Due to non-availability of vacant ' $d$ ' orbital.

NEET - 2018

CHXI11:THE P-BLOCK ELEMENTS

316233 Assertion :
Although ${PF}_{5}, {PCl}_{5}$ and ${PBr}_{5}$ are known, the pentahalides of nitrogen have not been observed.
Reason :
Phosphorus has lower electronegativity than nitrogen

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:

Nitrogen does not have d orbitals, due to which it cannot have covalency beyond four. Therefore it cannot form pentahalides. Electronegativity of ' $N$ ' is more than ' $P$ '. But it is not the reason for given assertion. So option (2) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316216 The Lewis acid character of boron trihalides follows the order

1

{BF}_{3} > {BCl}_{3} > {BBr}_{3} > {BI}_{3}

2

{BI}_{3} > {BBr}_{3} > {BCl}_{3} > {BF}_{3}

3

{BBr}_{3} > {BI}_{3} > {BCl}_{3} > {BF}_{3}

4

{BCl}_{3} > {BF}_{3} > {BBr}_{3} > {BI}_{3}

Explanation:

Extent of back bonding reduces down the group leading to more Lewis acidic strength.
${BF}_{3} > {BCl}_{3} > {BBr}_{3} > {BI}_{3}$ (Extent of back bonding)
( $2 p - 2 p) (2 p - 3 p) (2 p - 4 p) (2 p - 5 p)$
So, ${BF}_{3} < {BCl}_{3} < {BBr}_{3} < {BI}_{3}$ (Lewis acidic nature).
On the basis of small bonding smaller be the halide atom, more effective the back bonding & shows less tendency to accept a pair of electrons.

JEE - 2023

CHXI11:THE P-BLOCK ELEMENTS

316214 Assertion :
Anhydrous ${AlCl}_{3}$ is covalent but hydrated ${AlCl}_{3}$ is ionic.
Reason :
In water, ${Al}_{2} {Cl}_{6}$ dissociates into hydrated ${Al}^{3 +}$ and ${Cl}^{-}$ ions due to high heat of hydration of these ions.

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:

When anhydrous ${AlCl}_{3}$ is dissolved in water, it changes to hydrated ${AlCl}_{3}$ , which is ionic in nature. The dimeric formula is retained in a non-polar solvent but is broken into ${Al}^{+ 3}$ and ${Cl}^{- 1}$ ions upon dissolution in water, due to the high heat of hydration. So, option (1) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316215 Which one of the following elements is unable to form ${MF}_{6}^{3 -}$ ion?

1

B

2

In

3

Al

4

Ga

Explanation:

Due to non-availability of vacant ' $d$ ' orbital.

NEET - 2018

CHXI11:THE P-BLOCK ELEMENTS

316233 Assertion :
Although ${PF}_{5}, {PCl}_{5}$ and ${PBr}_{5}$ are known, the pentahalides of nitrogen have not been observed.
Reason :
Phosphorus has lower electronegativity than nitrogen

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:

Nitrogen does not have d orbitals, due to which it cannot have covalency beyond four. Therefore it cannot form pentahalides. Electronegativity of ' $N$ ' is more than ' $P$ '. But it is not the reason for given assertion. So option (2) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316216 The Lewis acid character of boron trihalides follows the order

1

{BF}_{3} > {BCl}_{3} > {BBr}_{3} > {BI}_{3}

2

{BI}_{3} > {BBr}_{3} > {BCl}_{3} > {BF}_{3}

3

{BBr}_{3} > {BI}_{3} > {BCl}_{3} > {BF}_{3}

4

{BCl}_{3} > {BF}_{3} > {BBr}_{3} > {BI}_{3}

Explanation:

Extent of back bonding reduces down the group leading to more Lewis acidic strength.
${BF}_{3} > {BCl}_{3} > {BBr}_{3} > {BI}_{3}$ (Extent of back bonding)
( $2 p - 2 p) (2 p - 3 p) (2 p - 4 p) (2 p - 5 p)$
So, ${BF}_{3} < {BCl}_{3} < {BBr}_{3} < {BI}_{3}$ (Lewis acidic nature).
On the basis of small bonding smaller be the halide atom, more effective the back bonding & shows less tendency to accept a pair of electrons.

JEE - 2023