Question

Which of the following statements about lanthanides is incorrect?

• A. All lanthanides are highly dense metals
• B. More characteristic oxidation state of lanthanides is $+3$
• C. Lanthanides are separated from one another by ion exchange method
• D. Ionic radii of trivalent lanthanides steadily increase with increase in atomic number

Answer 1

The correct option is D Ionic radii of trivalent lanthanides steadily increase with increase in atomic number

The statement- D, regarding the Lanthanides is incorrect. We are knowing that lanthanide contraction, in chemistry, is the steady decrease in the size of the atoms and ions of the rare earth elements with increasing atomic number. It ranges from lanthanum with atomic number 57 through lutetium with atomic number 71.

The ionic radii of the trivalent lanthanides steadily decrease with an increase in the atomic number. Other properties are true with lanthanides.

The correct option is D.