d and f BLOCK ELEMENTS

Which lanthanoid commonly exhibits the +2 oxidation state in its compounds?

• Samarium (Sm)
• Europium (Eu)
• Gadolinium (Gd)
• Terbium (Tb)

Which lanthanoid commonly exhibits the +4 oxidation state in its compounds?

• Lanthanum (La)
• Neodymium (Nd)
• Cerium (Ce)
• Europium (Eu)

What is a significant difference in the chemistry of early lanthanoids (like La, Ce) compared to later ones (like Yb, Lu) due to the lanthanoid contraction?

• Early lanthanoids are more radioactive
• Later lanthanoids tend to form more stable complexes
• Early lanthanoids are less abundant
• Later lanthanoids have higher melting points

How does the lanthanoid contraction affect the basicity of Ln(OH)₃ hydroxides?

• It causes the basicity to increase from La(OH)₃ to Lu(OH)₃
• It has no effect on basicity
• It causes the basicity to decrease from La(OH)₃ to Lu(OH)₃
• It makes all Ln(OH)₃ equally basic

What is the consequence of the lanthanoid contraction on the ionic radii of Ln³⁺ ions across the series?

• A gradual increase in ionic radius from La³⁺ to Lu³⁺
• No significant change in ionic radius
• A gradual decrease in ionic radius from La³⁺ to Lu³⁺
• An irregular fluctuation in ionic radius