The radius of the Bohr orbit in the ground state of hydrogen atom is `0.5 Å`. The radius o fthe orbit of the electron in the third excited state of `He^(+)` will be

Options

A. `8 Å`
B. `4 Å`
C. `0.5Å`
D. `0.25 Å`

Answer

B

Explanation

By using `r_(n) = r_(0) (n^(2))/(Z)`, where `r_(0) =` Radius of the Bohr orbit in the ground state atom. So for `He^(+)` third excited state `n = 4, Z = 2, r_(0) = 0.5 Å rArr r_(4) = 0.5 xx (4^(2))/(2) = 4 Å`