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. `Li^(2+) (n=2)`
C. `Li^(2+) (n=3)`
D. `Be^(3+) (n=2)`

Answer

D

Explanation

`r_(n)=0.529(n^(2))/(Z)`Å
For hydrogen, `n=1 and Z=I , therefore r_(H)=0.529`
For `Be^(3+), n=2 and Z=4`,
`therefore r_(Be^(3+))=(0.529xx2^(2))/(4)=0.529`