Question

Which of the following trivalent ion has the largest atomic radii in the lanthanide series?

(a) Lu

(b) Ce

(c) Gd

(d) La

Answer 1

Answer is : (d) La

In 4f-series, as the atomic number increases from La to Lu, the atomic and ionic radii decreases gradually due to lanthanide contraction. Thus, lanthanum (La) has the largest atomic radii in the lanthanide series.