Question

Which state of triply ionised Beryllium $\left(B{e}^{+++}\right)$ has the same orbital radius as that of the ground state of hydrogen ?

• A. $n=3$
• B. $n=4$
• C. $n=1$
• D. $n=2$

Answer 1

The correct option is D $n=2$

From Bohr's atomic model, atomic radius for $n$th state is given by the formula,

$r=0.059\frac{n^2}{z}A$

Since for Be, $z=4$

$\frac{n^2}{4}=\frac{1^2}{1}$

Hence, $n=2$