d and f BLOCK ELEMENTS

How do the metallic radii variations in actinoids compare to those in lanthanoids regarding structural variability?

• Lanthanoid variations are greater
• They are the same
• Actinoid variations are smaller
• Actinoid metallic radii variations are greater, leading to more structural variability

Which element is the first in the actinoid series where 5f orbital filling is formally considered to begin?

• Actinium (Ac)
• Thorium (Th)
• Protactinium (Pa)
• Uranium (U)

What is the relationship between the energy levels of 5f, 6d, and 7s orbitals in actinoids?

• 5f is much lower than 6d and 7s
• 7s is much lower than 5f and 6d
• 6d is much higher than 5f and 7s
• They are of comparable energies

Which actinoid ion is specifically mentioned as tending to hydrolyse?

• Only +3 ions
• Only +4 ions
• Both +3 and +4 ions
• Only +5 ions

What is the main reason actinoid contraction is greater than lanthanoid contraction?

• Larger atomic numbers
• Stronger nuclear forces
• Weaker shielding effect of 5f electrons compared to 4f electrons
• Smaller ionic radii initially