The dand fblock elements - Result Question 79
####79. The correct order of ionic radii of $Y^{3+}, La^{3+}, Eu^{3+}$ and $Lu^{3+}$ is
[2003]
(a) $La^{3+}<Eu^{3+}<Lu^{3+}<Y^{3+}$
(b) $Y^{3+}<La^{3+}<Eu^{3+}<Lu^{3+}$
(c) $Y^{3+}<Lu^{3+}<Eu^{3+}<La^{3+}$
(d) $Lu^{3+}<Eu^{3+}<La^{3+}<Y^{3+}$
(Atomic nos. $Y=39, La=57, Eu=63, Lu=71$ )
Show Answer
Solution:
- (c) In lanthanide series there is a regular decrease in the atomic as well as ionic radii of trivalent ions $(M^{3+})$ as the atomic number increases. Although the atomic radii do show some irregularities but ionic radii decreases from $La(103 pm)$ to $Lu(86 pm)$.
