Question

The correct order of atomic radii is:

• 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

The correct option is A $Y{b}^{3+}<P{m}^{3+}<C{e}^{3+}<L{a}^{3+}$

Ionic radii decrease as we move across the lanthanide series due to lanthanide contraction.

As all ions are in $+3$ oxidation state, ionic radii will follow the trend of atomic radii:

$Y{b}^{3+}<P{m}^{3+}<C{e}^{3+}<L{a}^{3+}$

(Atomic number of $La=57,Ce=58,Pm=61,Yb=70$)

Hence, option A is correct.