Question

Hydrogen atoms are excited from ground state to n = 6. Then the number of emission spectral lines observed will be –

• A. 3
• B. 10
• C. 15
• D. 21

Answer 1

Answer: (C)

15

Answer 2

No. of emission spectral lines = $\frac{n(n - 1)}{2}$

= $\frac{6(6 - 1)}{2}$ = 15