In oxygen gas burned so there are several atoms of the hydrogen atom which hydrogen atomic energy, each will get a job. Thus evolve energy. Several lines of spectrum
The oxygen used to burn the hydrogen atoms are many. The hydrogen atoms are given power not equal. Then spit out of unequal power. Causing many spectral lines
In the oxygen used burn is a hydrogen atom are many atoms. The hydrogen atom energy each will be uneven. Therefore emit energy out are not equal. Cause many spectrum lines.