Question

If $a_0$ is the Bohr radius, the radius of then n = 2 electronic orbit in triply ionized beryllium is:

• A. $4a_0$
• B. $a_0$
• C. $a_0/4$
• D. $a_0/16$

Answer 1

The correct option is B $a_0$

The radius for hydrogen equivalent system having atomic number $Z$

is given as $r_n=\frac{n^2{a}_0}{Z}$

Triply inonized Beryllium$(Z=4)$ means $single$ electron system.

for given system $Z=4$ and $n=2$ so $r_2=a_0$

Option B is correct.