Question

What is correct order of size in each pair given below ?

$Y^{3+}$ and $L{a}^{3+}$

• A. $Y^{3+}$ = $L{a}^{3+}$
• B. $Y^{3+}$ < $L{a}^{3+}$
• C. $Y^{3+}$ > $L{a}^{3+}$
• D. None of these

Answer 1

The correct option is B $Y^{3+}$ < $L{a}^{3+}$

The correct order of ionic radii is $Y^{3+}$ < $L{a}^{3+}$ $Y^{3+}$ has stable configuration of $Kr$. $L{a}^{3+}$ has stable configuration of $Xe$ and has more number of orbitals (one more orbit than that of $Y^{3+}$) which increases the size of $L{a}^{3+}$Option (B) is correct.