Question

when electron is in shell n= 3 how many spectral lines are possible??​

Answer 1

Total 4 spectral lines are possible.

One atom from n=4 to n=3 (L1)

then n=3 to n=2,(L2)

then n=2 to n=1. (L3)

Second electron from can come to ground state in either of the following way ( so that different/ separate line can be observed in spectrum)

Path 1: N=4 to n=3 (identical to L1 of frist atom so contribute to same line in spectrum)

Then n=3 to n=1 ( L4)

Or

Path 2: n=4 to n=2 (L5)

Then n=2 to n=1 (identical to L3 of frist atom so contribute to same line in spectrum)

Since there are only two atoms following lines will be observed

L1,L2, L3 and L4 or

L1,L2, L3 and L5