Question

Arrange $C{e}^{3+},L{a}^{3+}P{m}^{3+}$ and $Y{b}^{3+}$ in increasing order of their ionic radii

• A. $Y{b}^{3+}<P{m}^{3+}<C{e}^{3+}<L{a}^{3+}$
• B. $C{e}^{3+}<Y{b}^{3+}<P{m}^{3+}<L{a}^{3+}$
• C. $Y{b}^{3+}<P{m}^{3+}<L{a}^{3+}<C{e}^{3+}$
• D. $P{m}^{3+}<L{a}^{3+}<C{e}^{3+}<Y{b}^{3+}$

Answer 1

Answer: (A)

Ionic radii decrease as we move across lanthanide series due to lanthanide contraction. As all ion are in 3 + oxidation state, ionic radii will follow the trend of atomic radii
$L{a}^{3+}>C{e}^{3+}>P{m}^{3+}>Y{b}^{3+}$
$Y{b}^{3+}<P{m}^{3+}<C{e}^{3+}<L{a}^{3+}$
[At. No. La = 57, Ce = 58, Pm = 61, Yb = 70]