Question

When the electron in a H-atom jumps from 6th excited state to 2nd excited state, the maximum number of emission lines will be.

• A. $20$
• B. $18$
• C. $10$
• D. $5$

Answer 1

The correct option is B $18$

Number lines = $\begin{array}{c}\frac{n\left(n-1\right)}{2}\\ \frac{7\left(7-1\right)}{2}-\frac{3\left(3-1\right)}{2}=21-3=18\end{array}$