A 12 . 5 eV electron beam is used to bombard gaseous hydrogen at room temperature. The number of spectral lines emitted will be:

Step-by-step solution

According to Bohr's postulates, if an electron absorbs a photon with energy equal to the difference between the energies of an excited state and the ground state, it will jump to a higher energy orbital. Considering that the energy of the colliding electron is 10 . 2   eV or 12 . 09   eV , depending on how much energy is lost during the collision. n = 3 is the maximum excited state. Hence, there are spectral lines in a total of C 2 3 = 3 ! 2 ! 1 ! = 3