The radius of hydrogen atom in its ground state is `5.3 xx 10^-11 m`. After collision with an electron it is found to have a radius of `21.2 xx 10^-11 m`. The principal quantum number of the final state of the atom is.

Options

A. n=4
B. n=4
C. n=16
D. n=3

Answer

B

Explanation

` r prop n^(2)`
i.e, ` (r_(f))/( r_(i))=((n_(f))/(n_(i)))^(2)`
`implies (21.2 xx 10^(-11))/(5.3xx10^(-11))=[(n)/(1)]^(2)`
`implies n^(2)=4`
`implies n=2 `