Find the quantum number of the excited state of the electron of hydrogen atom if it absorbs photon of energy 12.09 eV.

The energy of an electron in nth orbit of H atom is E=−13.6n2eVFor the transition from the ground state to the nth state, the energy differenceis ΔE=−13.6112−1n2But this corresponds to 12.09 eVHence, −12.09=−13.6112−1n2⇒n=3