$A$ hypothetical atom has only three energy levels. The ground level has energy,$E_1 = -8 \ eV$. The two excited states have energies,$E_2 = -6 \ eV$ and $E_3 = -2 \ eV$. Which of the following wavelengths will $NOT$ be present in the emission spectrum of this atom (in $nm$)?

In the Bohr model of the hydrogen atom,the lowest orbit corresponds to:

The energy of a hydrogen atom in its ground state is $-13.6 \, eV$. The energy of the level corresponding to the quantum number $n = 5$ is ...... $eV$.

The diagram below shows the lowest four energy levels for an electron in a hypothetical atom. The electron is excited to the $-1\,eV$ level and transitions to the lowest energy state $(-12\,eV)$ by emitting exactly two photons. Which of the following energies could not belong to either of the photons (in $eV$)?

The four lowest energy levels of an $H$-atom are shown in the figure. The number of possible emission lines would be

If an electron in the excited state falls to the ground state,a photon of energy $5 \ eV$ is emitted. The wavelength of the photon is nearly: (in $nm$)