For a hydrogen atom,the energy of the $n^{th}$ orbit is given by the equation $E \propto n^y$. What is the value of $y$?

The energy of a photon is calculated by ......

The radius of the first excited state of a Helium ion $(He^+)$ is given by (where $a_0$ is the radius of the first stationary state of the hydrogen atom):

Find out the distance between the $2^{nd}$ and $3^{rd}$ orbit of the $H$-atom $:-$

When an electron drops from a higher energy level to a lower energy level,then

The space between the proton and the electron in a hydrogen atom is: