The ionization energy of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are excited by electromagnetic radiation of energy 12.1 eV. How many spectral lines will be emitted by the hydrogen atom?

Options

A. one
B. two
C. three
D. four

Answer

C

Explanation

When an electron in the ground state receives 12.1 eV of energy, it jumps to a level where its energy= 13.6 - 12.1 = 1.5 eV. This corresponds to the third excited state corresponding ton=3. It can have three transitions, namely from n = 3 to n = 2, from n = 2 to n = 1 and from n = 3 to n = 1. Hence three spectral lines will be emitted.