When a hydrogen atom emits a photon during a transition from $n=4$ to $n=2$,its recoil speed is about (in $m \ s^{-1}$)

If $13.6 \ eV$ energy is required to ionize the hydrogen atom,then the energy required to remove an electron from $n=2$ is (in $eV$)

The energy levels for an electron in a certain atom are shown in the figure. Which of the following transitions will emit a photon with the highest energy?

The energy of an electron in the fourth excited state of the hydrogen atom is

The following diagram indicates the energy levels of a certain atom. When the system moves from the $2E$ level to the $E$ level, it emits a photon of wavelength $\lambda$. What is the wavelength of the photon produced during its transition from the $\frac{4E}{3}$ level to the $E$ level?

In a hydrogen-like atom,when an electron jumps from the $M$-shell to the $L$-shell,the wavelength of the emitted radiation is $\lambda$. If an electron jumps from the $N$-shell to the $L$-shell,the wavelength of the emitted radiation will be: