Given below are two statements: 
Assertion (A): Ionisation enthalpies of early actinoids are lower than for early lanthanoids.
Reason (R): Electrons are entering 5f orbitals in actinoids which experience greater shielding from nuclear charge.
 
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. (A) is False but (R) is True.
Subtopic:  f-Block Elements- Properties & Uses |
From NCERT
NEET - 2023
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Gadolinium has a low value of third ionisation enthalpy because of:
1. high basic character 2. small size
3. high exchange enthalpy 4. high electronegativity
Subtopic:  f-Block Elements- Properties & Uses |
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From NCERT
NEET - 2022
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Identify the incorrect statements related to lanthanons:
 

1. Europium shows +2 oxidation state.
2. The basicity decreases as the ionic radius decreases from Pr to Lu.
3. All the lanthanons are much more reactive than aluminium.
4. Ce+4 solutions are widely used as oxidizing agents in volumetric analysis.
Subtopic:  f-Block Elements- Properties & Uses |
 68%
From NCERT
NEET - 2016
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The electronic configurations of Eu (Atomic no. 63), Gd (Atomic no. 64), and Tb (Atomic no. 65) are, respectively:
 
1. [Xe] 4f5d6s2, [Xe]4f5d6s2, and [Xe] 4f6s2
2. [Xe] 4f5d6s2, [Xe] 4f75d1 6s2, and [Xe]4f5d6s2
3. [Xe] 4f6s2, [Xe]4f7 5d6s2, and [Xe] 4f9 6s2
4. [Xe] 4f6s2, (Xe]4f6s2, and [Xe]4f8 5d6s2
Subtopic:  f-Block Elements- Properties & Uses |
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From NCERT
NEET - 2016
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Gadolinium belongs to 4f series. It’s atomic number is 64. Which of the following is the correct electronic configuration of gadolinium?

1. Xe4 f8 6d2

2. Xe4 f9 5s1

3. Xe4 f7 5d16s2

4. Xe4 f6 5d26s2

Subtopic:  f-Block Elements- Properties & Uses |
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From NCERT
NEET - 2015
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A pair among the following have nearly the same atomic radii:

(Numbers in the parenthesis are atomic numbers).

1. Ti (22) and Zr (40)
2. Zr (40) and Nb (41)
3. Zr (40) and Hf (72)
4. Zr (40) and Ta (73)

Subtopic:  f-Block Elements- Properties & Uses | Lanthanoid & Actinoids Contraction |
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From NCERT
NEET - 2015
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Diamagnetic lanthanoid ion among the following is:
(At nos. Ce = 58, Sm = 62, Eu = 63, Yb = 70)
1. Sm2+
2. Eu2+
3. Yb2+
4. Ce2+
Subtopic:  f-Block Elements- Properties & Uses |
 61%
From NCERT
AIPMT - 2013
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Actinoids exhibit more number of oxidation states than lanthanoids. It is because of: 
1. The greater metallic character of the lanthanoids than that of the corresponding actinoids.
2. More energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals.
3. The lesser energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals.
4. More active nature of the actinoids.
Subtopic:  d-Block Elements- Properties & Uses | f-Block Elements- Properties & Uses | Lanthanoid & Actinoids Contraction |
 79%
From NCERT
AIPMT - 2011
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Lanthanoid's most common oxidation state is:
1. 2
2. 5 
3. 3 
4. 4

Subtopic:  f-Block Elements- Properties & Uses |
 89%
From NCERT
AIPMT - 2010
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Actinoids exhibit more oxidation states than lanthanoids. The main reason for this is:

1. More energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals
2. Greater metallic character of the lanthanoids than that of the corresponding actinoids
3. The lesser energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals
4. More active nature of the actinoids

Subtopic:  f-Block Elements- Properties & Uses |
 62%
From NCERT
AIPMT - 2006
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