d and f BLOCK ELEMENTS

Which of the following best summarizes the electronic configuration of the most stable ion formed by Lanthanum (La)?

• 4f⁰
• 4f¹
• 4f²
• 5d¹

What is the significance of the statement that the shielding of one 4f electron by another is 'less' than one d electron by another?

• It explains why the lanthanoid contraction is more pronounced than typical d-block contractions
• It means 4f electrons are completely unshielded
• It indicates 4f electrons shield better than s electrons
• It shows d electrons provide no shielding

How does the text reconcile the fact that Ce⁴⁺ is a strong oxidant with its use as a good analytical reagent?

• By noting the reaction rate with water is very slow
• By stating Ce⁴⁺ is not actually a strong oxidant
• By saying it only works in basic solutions
• By claiming it's inexpensive

Which of the following Lanthanoids is explicitly mentioned as exhibiting both +2 and +3 oxidation states, similar to Europium?

• Samarium
• Gadolinium
• Lutetium
• Neodymium

What is the main reason given for the occasional formation of +2 and +4 oxidation states in Lanthanoids?

• Extra stability from specific f-subshell configurations (empty, half-filled, or filled)
• Lower ionization energies for the second and fourth electrons
• Higher electronegativity
• Greater atomic radii