Suppose the ionization energy of a hydrogen-like species is $960 \ eV$. The value of the principal quantum number for an energy level of $-60 \ eV$ will be $......$.

The Balmer series in the hydrogen spectrum corresponds to the transition from $n_1 = 2$ to $n_2 = 3, 4, ...$ This series lies in the visible region. Calculate the wave number of the line associated with the transition in the Balmer series when the electron moves to the $n = 4$ orbit. $(R_H = 109677 \ cm^{-1})$

If the energies of two light radiations $E_1$ and $E_2$ are $25 \ eV$ and $100 \ eV$ respectively,then their respective wavelengths $\lambda_1$ and $\lambda_2$ would be in the ratio $\lambda_1: \lambda_2=$

Supposing the electron is present in the $4^{th}$ energy level of $H$ atom. When the electron returns to the ground state,the possible transitions would be:

Which hydrogen-like species will have the same radius as that of the $1^{st}$ Bohr orbit of a hydrogen atom?

What is the difference between a photon and a quantum?