d and f BLOCK ELEMENTS

What is the most stable oxidation state for Plutonium (Pu) in aqueous solution?

• +3
• +4
• +5
• +6

What is the most stable oxidation state for Neptunium (Np) in aqueous solution?

• +3
• +4
• +5
• +6

Which actinoid element is the first one that occurs naturally in significant quantities (not just traces)?

• Thorium (Th)
• Protactinium (Pa)
• Uranium (U)
• Neptunium (Np)

What is the name given to the steady decrease in atomic/ionic radii across the actinoid series?

• Actinoid expansion
• Actinoid stabilization
• Actinoid contraction
• Actinoid shielding

What is the primary reason for the radioactivity of all actinoids?

• They have unpaired electrons
• They are synthetic elements
• Their atomic nuclei contain too many protons and neutrons to be stable
• They have high atomic masses