In a hydrogen atom, how many times is the radius of fourth orbit compared to that in the second orbit?

Explanation

If the principal quantum number of an orbit be n,then radius `r_nprop n^2`
`therefore ("radius of fourth orbit")/("radius of second orbit ")=(4)^2/(2)^2=(16)/(4)=4`
Therefore, the radius of fourth orbit is 4 times than the radius of second orbit.