Question

An electron jumps from sixth energy level to third energy level in Hydrogen atom, how many lines belong to the visible region?
(A) $ 1 $
(B) $ 2 $
(C) $ 3 $
(D) Zero

Answer 1

Hint: We know that in order to solve this question we must know little basic information like what is meant by spectral lines. Spectral series are said to be the set of wavelengths arranged in a sequential fashion which characterizes light or any electromagnetic radiation emitted by the energized atoms.

Complete answer:
When a substance absorbs energy, it emits radiation. Spectrum of such radiation is called the emission spectrum. Atoms, molecules or ions that absorb radiation are called excited. Spectrum of visible light is continuous. Spectrum of atoms in gaseous state does not show a continuous spectrum but they emit light at specific wavelengths with dark spaces between them. Such a spectrum is called the line spectrum or atomic spectrum. Line emission spectrums are important to understand electronic structure. Each element has a unique line emission spectrum. When an electric discharge is passed through gaseous hydrogen, hydrogen molecules dissociate and energetically excited hydrogen atoms produce electromagnetic radiation of discrete frequencies. Hydrogen spectrum consists of several series of lines named after discoveries.
Hydrogen atom is said to be the simplest atomic system found in nature, thus it produces the simplest of the spectral series. When electrons de-excite from higher energy level $ \left( {{n}_{2}} \right) $ to lower energy level $ \left( {{n}_{1}} \right) $ in atomic sample, then number of spectral line observed in the spectrum. Transitions between the sixth and third transition series give spectral lines in the infrared region and not visible region. Since no spectral lines will be obtained, if you want to obtain lines in the visible region the electron must jump to the second energy shell (balmer).
Therefore, the correct answer is option D i.e. an electron jumps from sixth energy level to third energy level in Hydrogen atom; zero lines belong to the visible region.

Note:
Remember that the spectrum of visible light is continuous. Spectrums of atoms in gaseous state do not show continuous spectrum but they emit light at specific wavelengths with dark spaces between them. Such a spectrum is called the line spectrum or atomic spectrum.