An electron with kinetic energy $E$ collides with a hydrogen atom in the ground state. The collision will be elastic

The ratio of energies of photons produced due to transition of an electron in a hydrogen atom from the second energy level to the first energy level and from the fifth energy level to the second energy level is:

The $1^{st}, 2^{nd},$ and $3^{rd}$ energy levels of an atom are $E, 4E/3,$ and $2E$ respectively. If a wavelength $\lambda$ is emitted during the transition $3 \to 1$,what is the wavelength emitted during the transition $2 \to 1$?

$A$ hydrogen atom is bombarded with electrons accelerated through a potential difference of $V$, which causes excitation of hydrogen atoms. If the experiment is performed at $T = 0 \,K$, the minimum potential difference needed to observe any Balmer series lines in the emission spectra will be $\frac{\alpha}{10} \,V$, where $\alpha = $ . . . . . . .

$A$ hydrogen atom (ionisation potential $13.6 \ eV$) makes a transition from the third excited state to the first excited state. The energy of the photon emitted in the process is.......$eV$.

An electron of a hydrogen atom in an excited state has an energy $E_n = -0.85 \ eV$. The maximum number of allowed transitions to lower energy levels is: