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CHXI11:THE P-BLOCK ELEMENTS

316468 Assertion :
The first member of a group of elements compared to that of the subsequent members in the same group shows different chemical behaviour.
Reason :
The first member of a group has small size, high electronegativity and no $d$ -orbital.

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:

Besides its small size and high electronegativity, the first member of each group has only four valence orbitals $( 2s and 2p )$ available for bonding, meaning there is no expansion of the valence shell to accommodate more than four pairs of electrons, So, option (1) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316469 Assertion :
$Al$ forms ${[{AlF}_{6}]}^{3 -}$ but $B$ does not form ${[{BF}_{6}]}^{3 -}$ .
Reason :
B does not react with fluorine.

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:

Boron does not expand its octet due to non availability of vacant d-orbitals (sub-shell) in its valence shell, but alluminium can . Boron reacts with $F_{2}$ to form boron trifluorides. So, option (3) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316470 Boron cannot form which one of the following anions?

1

{BF}_{6}^{3 -}

2

{BH}_{4}^{-}

3

B (OH)_{4}^{-}

4

{BO}_{2}^{-}

Explanation:

Due to absence of d-orbitals, B cannot extend its co-valency beyond 4 and hence it forms only ${BF}_{4}^{-}$ and not ${BF}_{6}^{3 -}$ .

CHXI11:THE P-BLOCK ELEMENTS

316471 Statement A :
Boron always forms covalent bond.
Statement B :
The small size of $B^{3 +}$ favours formation of covalent bond.

1 Statement A is correct but Statement B is incorrect.

2 Statement A is incorrect but Statement B is correct.

3 Both statements are correct.

4 Both Statements are incorrect.

Explanation:

Boron always forms covalent bond because of its small size. $B$ never forms $B^{3 +}$ ion.

CHXI11:THE P-BLOCK ELEMENTS

316468 Assertion :
The first member of a group of elements compared to that of the subsequent members in the same group shows different chemical behaviour.
Reason :
The first member of a group has small size, high electronegativity and no $d$ -orbital.

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:

Besides its small size and high electronegativity, the first member of each group has only four valence orbitals $( 2s and 2p )$ available for bonding, meaning there is no expansion of the valence shell to accommodate more than four pairs of electrons, So, option (1) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316469 Assertion :
$Al$ forms ${[{AlF}_{6}]}^{3 -}$ but $B$ does not form ${[{BF}_{6}]}^{3 -}$ .
Reason :
B does not react with fluorine.

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:

Boron does not expand its octet due to non availability of vacant d-orbitals (sub-shell) in its valence shell, but alluminium can . Boron reacts with $F_{2}$ to form boron trifluorides. So, option (3) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316470 Boron cannot form which one of the following anions?

1

{BF}_{6}^{3 -}

2

{BH}_{4}^{-}

3

B (OH)_{4}^{-}

4

{BO}_{2}^{-}

Explanation:

Due to absence of d-orbitals, B cannot extend its co-valency beyond 4 and hence it forms only ${BF}_{4}^{-}$ and not ${BF}_{6}^{3 -}$ .

CHXI11:THE P-BLOCK ELEMENTS

316471 Statement A :
Boron always forms covalent bond.
Statement B :
The small size of $B^{3 +}$ favours formation of covalent bond.

1 Statement A is correct but Statement B is incorrect.

2 Statement A is incorrect but Statement B is correct.

3 Both statements are correct.

4 Both Statements are incorrect.

Explanation:

Boron always forms covalent bond because of its small size. $B$ never forms $B^{3 +}$ ion.

CHXI11:THE P-BLOCK ELEMENTS

316468 Assertion :
The first member of a group of elements compared to that of the subsequent members in the same group shows different chemical behaviour.
Reason :
The first member of a group has small size, high electronegativity and no $d$ -orbital.

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:

Besides its small size and high electronegativity, the first member of each group has only four valence orbitals $( 2s and 2p )$ available for bonding, meaning there is no expansion of the valence shell to accommodate more than four pairs of electrons, So, option (1) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316469 Assertion :
$Al$ forms ${[{AlF}_{6}]}^{3 -}$ but $B$ does not form ${[{BF}_{6}]}^{3 -}$ .
Reason :
B does not react with fluorine.

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:

Boron does not expand its octet due to non availability of vacant d-orbitals (sub-shell) in its valence shell, but alluminium can . Boron reacts with $F_{2}$ to form boron trifluorides. So, option (3) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316470 Boron cannot form which one of the following anions?

1

{BF}_{6}^{3 -}

2

{BH}_{4}^{-}

3

B (OH)_{4}^{-}

4

{BO}_{2}^{-}

Explanation:

Due to absence of d-orbitals, B cannot extend its co-valency beyond 4 and hence it forms only ${BF}_{4}^{-}$ and not ${BF}_{6}^{3 -}$ .

CHXI11:THE P-BLOCK ELEMENTS

316471 Statement A :
Boron always forms covalent bond.
Statement B :
The small size of $B^{3 +}$ favours formation of covalent bond.

1 Statement A is correct but Statement B is incorrect.

2 Statement A is incorrect but Statement B is correct.

3 Both statements are correct.

4 Both Statements are incorrect.

Explanation:

Boron always forms covalent bond because of its small size. $B$ never forms $B^{3 +}$ ion.

CHXI11:THE P-BLOCK ELEMENTS

316468 Assertion :
The first member of a group of elements compared to that of the subsequent members in the same group shows different chemical behaviour.
Reason :
The first member of a group has small size, high electronegativity and no $d$ -orbital.

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:

Besides its small size and high electronegativity, the first member of each group has only four valence orbitals $( 2s and 2p )$ available for bonding, meaning there is no expansion of the valence shell to accommodate more than four pairs of electrons, So, option (1) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316469 Assertion :
$Al$ forms ${[{AlF}_{6}]}^{3 -}$ but $B$ does not form ${[{BF}_{6}]}^{3 -}$ .
Reason :
B does not react with fluorine.

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:

Boron does not expand its octet due to non availability of vacant d-orbitals (sub-shell) in its valence shell, but alluminium can . Boron reacts with $F_{2}$ to form boron trifluorides. So, option (3) is correct.

CHXI11:THE P-BLOCK ELEMENTS

316470 Boron cannot form which one of the following anions?

1

{BF}_{6}^{3 -}

2

{BH}_{4}^{-}

3

B (OH)_{4}^{-}

4

{BO}_{2}^{-}

Explanation:

Due to absence of d-orbitals, B cannot extend its co-valency beyond 4 and hence it forms only ${BF}_{4}^{-}$ and not ${BF}_{6}^{3 -}$ .

CHXI11:THE P-BLOCK ELEMENTS

316471 Statement A :
Boron always forms covalent bond.
Statement B :
The small size of $B^{3 +}$ favours formation of covalent bond.

1 Statement A is correct but Statement B is incorrect.

2 Statement A is incorrect but Statement B is correct.

3 Both statements are correct.

4 Both Statements are incorrect.

Explanation:

Boron always forms covalent bond because of its small size. $B$ never forms $B^{3 +}$ ion.