The ionization potential of a hydrogen atom is $13.6 \text{ eV}$. How much energy needs to be supplied to ionize a hydrogen atom in the first excited state (in $\text{ eV}$)?

$A$ 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.......$eV$.

The diagram 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 by emitting exactly two photons. Which of the following energies could not belong to either of the photons (in $, eV$)?

When a hydrogen atom is raised from the ground state to the excited state,

An electron in a hydrogen atom undergoes a transition from an orbit with quantum number $n_i$ to another with quantum number $n_f$. $V_i$ and $V_f$ are respectively the initial and final potential energies of the electron. If $\frac{V_i}{V_f} = 6.25$,then the smallest possible $n_f$ is:

The total energy of a hydrogen atom in its ground state is $-13.6 \ eV$. If the potential energy in the first excited state is taken as zero,then the total energy in the ground state will be ..... $eV$.