The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom is

The radius of a hydrogen atom in the ground state is $0.53 \ Å$. After collision with an electron,it is found to have a radius of $2.12 \ Å$. The principal quantum number $n$ of the final state of the atom is:

The radius of the innermost electron orbit of a hydrogen atom is $5.3 \times 10^{-11} \;m$. What are the radii of the $n=2$ and $n=3$ orbits?

What is the ratio of the time periods of an electron in the $n = 2$ and $n = 1$ orbits of a hydrogen atom (in $:1$)?

In a hydrogen atom,let $R$,$v$,and $E$ denote the radius,velocity,and total energy of the electron,respectively. Then,the principal quantum number $n$ is proportional to which of the following?

The period of revolution of an electron revolving in $n^{th}$ orbit of $H$-atom is proportional to