In the hydrogen spectrum,the energy during the first Lyman transition is $E = 10.2 \ eV$. The same energy is observed during the second Balmer series transition in which of the following species?

The surface of sodium metal is irradiated with radiation of wavelength $x$ nm. The kinetic energy of ejected electrons is $2.8 \times 10^{-20}$ $J$. The work function of sodium is $2.3$ eV. The value of $x$ is . . . . . . $\times 10^2$ nm.

In a hydrogen atom,if $9 \, eV$ of energy is supplied,how many spectral lines will be emitted?

The frequency and energy of a photon with a wavelength of $4000 \ \mathring{A}$ are respectively.......

The longest wavelength of light that can be used for the ionisation of lithium atom $(Li)$ in its ground state is $x \times 10^{-8} \, m$. The value of $x$ is $.....$ (Nearest Integer)
(Given : Energy of the electron in the first shell of the hydrogen atom is $-2.2 \times 10^{-18} \, J$; $h = 6.63 \times 10^{-34} \, Js$ and $c = 3 \times 10^{8} \, ms^{-1}$ )

First and second excitation potentials of hydrogen atom (in $eV$) would be respectively