d and f BLOCK ELEMENTS

What is the primary difference in the electronic configurations of Eu²⁺ and Eu³⁺ ions?

• Eu²⁺ has a 4f⁷ configuration, while Eu³⁺ has a 4f⁶ configuration
• Eu²⁺ has a 4f⁶ configuration, while Eu³⁺ has a 4f⁷ configuration
• Eu²⁺ has a 4f⁸ configuration, while Eu³⁺ has a 4f⁷ configuration
• Eu²⁺ has a 4f⁷ configuration, while Eu³⁺ has a 5d¹ configuration

What is the primary difference in the electronic configurations of Ce³⁺ and Ce⁴⁺ ions?

• Ce³⁺ has a 4f¹ configuration, while Ce⁴⁺ has a 4f⁰ configuration
• Ce³⁺ has a 4f⁰ configuration, while Ce⁴⁺ has a 4f¹ configuration
• Ce³⁺ has a 4f² configuration, while Ce⁴⁺ has a 4f¹ configuration
• Ce³⁺ has a 5d¹ configuration, while Ce⁴⁺ has a 4f⁰ configuration

What is the significance of the statement 'The decrease in atomic radii... is not quite regular as it is regular in M³⁺ ions'?

• It highlights that the contraction is more predictable and consistent when observing the ions rather than the neutral atoms
• It means atomic radii decrease more than ionic radii
• It indicates that ionic radii do not change
• It suggests that atomic radii are always larger than ionic radii

Why are Pr, Nd, Tb, and Dy mentioned as exhibiting the +4 state only in oxides (MO₂)?

• The +4 state for these elements is stabilized specifically within the oxide lattice structure
• The +4 state is the most common state for these elements
• These elements cannot form +3 ions
• Oxides are the only compounds these elements can form

How does the text explain the difficulty in separating Zr and Hf?

• Their atomic radii are almost identical due to the lanthanoid contraction
• They have identical chemical properties
• They form the same types of compounds
• They have the same atomic number