Question

although only one electron is present in H-atom many spectral lines are observed in hydrogen spectrum.explain

Answer 1

Though a hydrogen atom has only one electron, it contains a large number of shells, so when this single electron jumps from one shell to another, a photon is emitted, and the energy difference of the shells causes different wavelengths to be released.Hence, mono-electronic hydrogen has many spectral lines.

Answer 2

The electron in the ground state gains energy and moves to a higher energy level,the excited state. The electron in excited state loses energy and comes back to ground state by emitting energy.Basing on the emitted energy,it forms different lines in the spectrum.