Ncert Exercises & Solutions

2.15 What is the maximum number of emission lines when the excited electron of a H atom in n = 6 drops to the ground state?

When the excited electron of an H atom in n = 6 drops to the ground state, the following transitions are possible:

Hence, a total number of (5 + 4 + 3 + 2 + 1) 15 lines will be obtained in the emission spectrum.

The number of spectral lines produced when an electron in the n
th level drops down to the ground state is given by $\frac{n (n - 1)}{2}$ .

Given, n = 6

Number of spectral lines = $\frac{6 (6 - 1)}{2}$ = 15