Question

Which state of triply ionised Baryllium $(Be^{+ + +})$ has the same orbital radius as that of the ground state of hydrogen.

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

Answer 1

Answer: (C)

n = 2

Answer 2

Radius of n^th orbit for any hydrogen like atom

$r_{n} = r_{0}\left( \frac{n^{2}}{Z} \right)$ ($r_{0} =$radius of first orbit of $H_{2}$-atom)

If $r_{n} = r_{0}$ ⇒ $n = \sqrt{Z}.$ For Be⁺⁺⁺, Z = 4 ⇒ n = 2.