Explain why the spectrum of hydrogen contains a number of lines although a hydrogen atom has only one electron.

Explanation

In hydrogen gas, there are innumerable hydrogen atoms, i.e ., in hydrogen discharge tube, there are innumerable electrons. Different electrons absorb different amounts of energy and get excited to different states . As a result , when they radiate energy, transitions occur between different pairs of states, for each transition, a spectral line is obtained. Thus , the spectum of hydrogen contains a number of lines .