The energy of an electron in the first excited state of an $H$-atom is $-3.4 \ eV$. Its kinetic energy is ........ $eV$.

In the Bohr model of the hydrogen atom,what is the energy required to remove an electron from the ground state $(n = 1)$ (in $eV$)?

The energy required to knock out the electron in the third orbit of a hydrogen atom is equal to

$\frac{x}{x+4}$ is the ratio of energies of photons produced due to the transition of an electron of a hydrogen atom from its $(i)$ third permitted energy level to the second level and $(ii)$ the highest permitted energy level to the second permitted level. The value of $x$ will be.

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

The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with maximum wavelength?