d and f BLOCK ELEMENTS

How do early actinoids resemble lanthanoids despite their differences?

• They have identical atomic radii.
• They only exhibit +3 oxidation state.
• They show close similarities with each other and gradual property changes.
• They are all radioactive.

At what point in the actinoid series does behavior similar to lanthanoids become evident?

• From the very first element.
• In the first quarter of the series.
• In the second half of the actinoid series.
• Only in the last element.

What is the consequence of outer electrons being less firmly held in actinoid atoms?

• They are less reactive.
• They have higher melting points.
• They are more readily available for chemical bonding.
• They are more stable.

Why are the ionization enthalpies of early actinoids generally lower than those of early lanthanoids?

• Actinoids have fewer protons.
• 5f electrons provide lesser shielding than 4f electrons.
• 5f electrons provide greater shielding than 4f electrons.
• Actinoids have larger atomic radii.

What accounts for the higher magnetic susceptibility values observed in lanthanoids compared to actinoids?

• Lanthanoids have more electrons.
• Actinoids are heavier elements.
• The different shielding and penetration of 4f versus 5f orbitals.
• Actinoids have paired electrons only.