The radius of which of the following orbit is same as that of the first Bohr's orbit of hydrogen atom.

Options

A. `He^+ (n = 2)`
B. `L i^(2 +)(n = 2)`
C. `Li^(2 +) (n = 3)`
D. `Be^(3 +) (n = 2)`

Answer

D

Explanation

(d) `r_n = 0.529 (n^2)/(Z) Å`
For hydrogen, `n = 1 and Z = 1` , `:. r_H = 0.529`
For `Be^(3 +), n = 2 and Z = 4`
`:. r_(Be^(3 +)) = (0.529 xx 2^2)/(4) = 0.529`.