Bohr's radius can have

If $m$ and $e$ are the mass and charge of the revolving electron in the orbit of radius $r$ for a hydrogen atom,the total energy of the revolving electron will be:

When $\beta$-particles are sent through a tin metal foil,most of them go straight through the foil as

The ratio between kinetic energy and the total energy of the electrons of a hydrogen atom according to Bohr's model is

What is the energy associated with the fourth orbit of a hydrogen atom?
$R_H = 2.18 \times 10^{-18} \ J$

In a hydrogen atom,if $9 \, eV$ of energy is supplied,how many spectral lines will be emitted?