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. `0.5 Å`
D. `0.25 Å`

Answer

B

Explanation

For third excited state, `n = 4`
`r_(n) = r_(0) (n^(2))/(2)`
or ` r_(1) = 0.5 xx (4 xx 4)/(2) Å = 4 Å`