Question

How many spectral lines are seen for hydrogen atom when electron jump from n=5 to n=1 in visible range?

Answer 1

If the electron jumps from $n_2=5$ to $n_1=1$ then following are the transitions possible.

1. $5-4$
   
2. $5-3$
   
3. $5-2$
   
4. $5-1$
   
5. $4-3$
   
6. $4-2$
   
7. $4-1$
   
8. $3-2$
   
9. $3-1$
   
10. $2-1$
    

Hence there are 10 transitions and hence 10 spectral lines possible.