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CHXII08:THE D- & F-BLOCK ELEMENTS

321667 The electronic configuration of Einsteinium is
(Given atomic number of Einsteinium $= 99$ )

1

[Rn] 5 f^{13} 6 d^{0} 7 s^{2}

2

[Rn] 5 f^{11} 6 d^{0} 7 s^{2}

3

[Rn] 5 f^{10} 6 d^{0} 7 s^{2}

4

[Rn] 5 f^{12} 6 d^{0} 7 s^{2}

Explanation:

Einsteinium (99) : $[R n] 5 f^{11} 6 d^{0} 7 s^{2}$
So, the correct option is (2).

JEE Main - 2024

CHXII08:THE D- & F-BLOCK ELEMENTS

321668 Which of the following is not an actinide?

1 Curium

2 Californium

3 Uranium

4 Terbium

Explanation:

Terbium is a lanthanide as it belongs to 4f-series having configuration $[X e] 4 f^{9}, 6 s^{2}$ . However, the remaining members belongs to 5f-series of actinides.

CHXII08:THE D- & F-BLOCK ELEMENTS

321669 The electronic configuration of actinoids cannot be assigned with degree of certainty because of

1 small energy difference between 5f and 6d levels

2 overlapping of inner orbitals

3 free movement of electrons over all the orbitals

4 none of the above.

Explanation:

For the first four actinide elements, $Th, Pa, U$ and $Np$ , the difference in energy between $5 f$ and $6 d$ -orbitals is small. Thus, in these elements (and their ions) electrons may occupy the $5 f$ or the $6 d$ levels or sometimes both. Later in the actinide series, the 5 -orbitals become appreciably lower in energy. Thus, from $Pu$ onwards the 5 -shell fills in a regular way and the elements become very similar.

CHXII08:THE D- & F-BLOCK ELEMENTS

321670 Which subshell is filled up progressively in actinoids?

1

4 f

2

5 f

3

6 d

4

7 s

Explanation:

In case of actinoids, $5 f$ orbital is progressively filled.

CHXII08:THE D- & F-BLOCK ELEMENTS

321671 Assertion :
Actinides are highly electropositive metals.
Reason :
Actinides have same valency.

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:

Actinides exhibit variable valency owing to the extremely small energy differences between their $5 f, 6 d$ , and $7 s$ orbitals. This proximity in energy levels allows for facile changes in oxidation states, contributing to the wide range of valencies observed in these elements. Therefore, option (3) is correct.

CHXII08:THE D- & F-BLOCK ELEMENTS

321667 The electronic configuration of Einsteinium is
(Given atomic number of Einsteinium $= 99$ )

1

[Rn] 5 f^{13} 6 d^{0} 7 s^{2}

2

[Rn] 5 f^{11} 6 d^{0} 7 s^{2}

3

[Rn] 5 f^{10} 6 d^{0} 7 s^{2}

4

[Rn] 5 f^{12} 6 d^{0} 7 s^{2}

Explanation:

Einsteinium (99) : $[R n] 5 f^{11} 6 d^{0} 7 s^{2}$
So, the correct option is (2).

JEE Main - 2024

CHXII08:THE D- & F-BLOCK ELEMENTS

321668 Which of the following is not an actinide?

1 Curium

2 Californium

3 Uranium

4 Terbium

Explanation:

Terbium is a lanthanide as it belongs to 4f-series having configuration $[X e] 4 f^{9}, 6 s^{2}$ . However, the remaining members belongs to 5f-series of actinides.

CHXII08:THE D- & F-BLOCK ELEMENTS

321669 The electronic configuration of actinoids cannot be assigned with degree of certainty because of

1 small energy difference between 5f and 6d levels

2 overlapping of inner orbitals

3 free movement of electrons over all the orbitals

4 none of the above.

Explanation:

For the first four actinide elements, $Th, Pa, U$ and $Np$ , the difference in energy between $5 f$ and $6 d$ -orbitals is small. Thus, in these elements (and their ions) electrons may occupy the $5 f$ or the $6 d$ levels or sometimes both. Later in the actinide series, the 5 -orbitals become appreciably lower in energy. Thus, from $Pu$ onwards the 5 -shell fills in a regular way and the elements become very similar.

CHXII08:THE D- & F-BLOCK ELEMENTS

321670 Which subshell is filled up progressively in actinoids?

1

4 f

2

5 f

3

6 d

4

7 s

Explanation:

In case of actinoids, $5 f$ orbital is progressively filled.

CHXII08:THE D- & F-BLOCK ELEMENTS

321671 Assertion :
Actinides are highly electropositive metals.
Reason :
Actinides have same valency.

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:

Actinides exhibit variable valency owing to the extremely small energy differences between their $5 f, 6 d$ , and $7 s$ orbitals. This proximity in energy levels allows for facile changes in oxidation states, contributing to the wide range of valencies observed in these elements. Therefore, option (3) is correct.

CHXII08:THE D- & F-BLOCK ELEMENTS

321667 The electronic configuration of Einsteinium is
(Given atomic number of Einsteinium $= 99$ )

1

[Rn] 5 f^{13} 6 d^{0} 7 s^{2}

2

[Rn] 5 f^{11} 6 d^{0} 7 s^{2}

3

[Rn] 5 f^{10} 6 d^{0} 7 s^{2}

4

[Rn] 5 f^{12} 6 d^{0} 7 s^{2}

Explanation:

Einsteinium (99) : $[R n] 5 f^{11} 6 d^{0} 7 s^{2}$
So, the correct option is (2).

JEE Main - 2024

CHXII08:THE D- & F-BLOCK ELEMENTS

321668 Which of the following is not an actinide?

1 Curium

2 Californium

3 Uranium

4 Terbium

Explanation:

Terbium is a lanthanide as it belongs to 4f-series having configuration $[X e] 4 f^{9}, 6 s^{2}$ . However, the remaining members belongs to 5f-series of actinides.

CHXII08:THE D- & F-BLOCK ELEMENTS

321669 The electronic configuration of actinoids cannot be assigned with degree of certainty because of

1 small energy difference between 5f and 6d levels

2 overlapping of inner orbitals

3 free movement of electrons over all the orbitals

4 none of the above.

Explanation:

For the first four actinide elements, $Th, Pa, U$ and $Np$ , the difference in energy between $5 f$ and $6 d$ -orbitals is small. Thus, in these elements (and their ions) electrons may occupy the $5 f$ or the $6 d$ levels or sometimes both. Later in the actinide series, the 5 -orbitals become appreciably lower in energy. Thus, from $Pu$ onwards the 5 -shell fills in a regular way and the elements become very similar.

CHXII08:THE D- & F-BLOCK ELEMENTS

321670 Which subshell is filled up progressively in actinoids?

1

4 f

2

5 f

3

6 d

4

7 s

Explanation:

In case of actinoids, $5 f$ orbital is progressively filled.

CHXII08:THE D- & F-BLOCK ELEMENTS

321671 Assertion :
Actinides are highly electropositive metals.
Reason :
Actinides have same valency.

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:

Actinides exhibit variable valency owing to the extremely small energy differences between their $5 f, 6 d$ , and $7 s$ orbitals. This proximity in energy levels allows for facile changes in oxidation states, contributing to the wide range of valencies observed in these elements. Therefore, option (3) is correct.

CHXII08:THE D- & F-BLOCK ELEMENTS

321667 The electronic configuration of Einsteinium is
(Given atomic number of Einsteinium $= 99$ )

1

[Rn] 5 f^{13} 6 d^{0} 7 s^{2}

2

[Rn] 5 f^{11} 6 d^{0} 7 s^{2}

3

[Rn] 5 f^{10} 6 d^{0} 7 s^{2}

4

[Rn] 5 f^{12} 6 d^{0} 7 s^{2}

Explanation:

Einsteinium (99) : $[R n] 5 f^{11} 6 d^{0} 7 s^{2}$
So, the correct option is (2).

JEE Main - 2024

CHXII08:THE D- & F-BLOCK ELEMENTS

321668 Which of the following is not an actinide?

1 Curium

2 Californium

3 Uranium

4 Terbium

Explanation:

Terbium is a lanthanide as it belongs to 4f-series having configuration $[X e] 4 f^{9}, 6 s^{2}$ . However, the remaining members belongs to 5f-series of actinides.

CHXII08:THE D- & F-BLOCK ELEMENTS

321669 The electronic configuration of actinoids cannot be assigned with degree of certainty because of

1 small energy difference between 5f and 6d levels

2 overlapping of inner orbitals

3 free movement of electrons over all the orbitals

4 none of the above.

Explanation:

For the first four actinide elements, $Th, Pa, U$ and $Np$ , the difference in energy between $5 f$ and $6 d$ -orbitals is small. Thus, in these elements (and their ions) electrons may occupy the $5 f$ or the $6 d$ levels or sometimes both. Later in the actinide series, the 5 -orbitals become appreciably lower in energy. Thus, from $Pu$ onwards the 5 -shell fills in a regular way and the elements become very similar.

CHXII08:THE D- & F-BLOCK ELEMENTS

321670 Which subshell is filled up progressively in actinoids?

1

4 f

2

5 f

3

6 d

4

7 s

Explanation:

In case of actinoids, $5 f$ orbital is progressively filled.

CHXII08:THE D- & F-BLOCK ELEMENTS

321671 Assertion :
Actinides are highly electropositive metals.
Reason :
Actinides have same valency.

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:

Actinides exhibit variable valency owing to the extremely small energy differences between their $5 f, 6 d$ , and $7 s$ orbitals. This proximity in energy levels allows for facile changes in oxidation states, contributing to the wide range of valencies observed in these elements. Therefore, option (3) is correct.

CHXII08:THE D- & F-BLOCK ELEMENTS

321667 The electronic configuration of Einsteinium is
(Given atomic number of Einsteinium $= 99$ )

1

[Rn] 5 f^{13} 6 d^{0} 7 s^{2}

2

[Rn] 5 f^{11} 6 d^{0} 7 s^{2}

3

[Rn] 5 f^{10} 6 d^{0} 7 s^{2}

4

[Rn] 5 f^{12} 6 d^{0} 7 s^{2}

Explanation:

Einsteinium (99) : $[R n] 5 f^{11} 6 d^{0} 7 s^{2}$
So, the correct option is (2).

JEE Main - 2024

CHXII08:THE D- & F-BLOCK ELEMENTS

321668 Which of the following is not an actinide?

1 Curium

2 Californium

3 Uranium

4 Terbium

Explanation:

Terbium is a lanthanide as it belongs to 4f-series having configuration $[X e] 4 f^{9}, 6 s^{2}$ . However, the remaining members belongs to 5f-series of actinides.

CHXII08:THE D- & F-BLOCK ELEMENTS

321669 The electronic configuration of actinoids cannot be assigned with degree of certainty because of

1 small energy difference between 5f and 6d levels

2 overlapping of inner orbitals

3 free movement of electrons over all the orbitals

4 none of the above.

Explanation:

For the first four actinide elements, $Th, Pa, U$ and $Np$ , the difference in energy between $5 f$ and $6 d$ -orbitals is small. Thus, in these elements (and their ions) electrons may occupy the $5 f$ or the $6 d$ levels or sometimes both. Later in the actinide series, the 5 -orbitals become appreciably lower in energy. Thus, from $Pu$ onwards the 5 -shell fills in a regular way and the elements become very similar.

CHXII08:THE D- & F-BLOCK ELEMENTS

321670 Which subshell is filled up progressively in actinoids?

1

4 f

2

5 f

3

6 d

4

7 s

Explanation:

In case of actinoids, $5 f$ orbital is progressively filled.

CHXII08:THE D- & F-BLOCK ELEMENTS

321671 Assertion :
Actinides are highly electropositive metals.
Reason :
Actinides have same valency.

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:

Actinides exhibit variable valency owing to the extremely small energy differences between their $5 f, 6 d$ , and $7 s$ orbitals. This proximity in energy levels allows for facile changes in oxidation states, contributing to the wide range of valencies observed in these elements. Therefore, option (3) is correct.