The no of spectial inser are observed is visible region when electron yumps from5thlevel to ground state

It seems like you're asking about the number of spectral lines observed in the visible region when an electron jumps from the 5th energy level to the ground state in an atom. Here's how you can calculate it:

1. The formula to calculate the number of spectral lines when an electron jumps from a higher energy level (n) to a lower energy level is n(n-1)/2.

2. In this case, the electron is jumping from the 5th energy level to the ground state (1st energy level). So, n = 5.

3. Substituting n = 5 in the formula, we get 5(5-1)/2 = 5*4/2 = 10.

So, there are 10 possible spectral lines when an electron jumps from the 5th energy level to the ground state.

However, not all of these lines will be in the visible region of the spectrum. The specific lines that appear in the visible region depend on the type of atom and the exact energy levels involved. For a hydrogen atom, the Balmer series of lines appear in the visible region, which involve transitions to the n=2 level. So, in this case, there would be 3 lines in the visible region (transitions from n=5 to n=2, n=4 to n=2, and n=3 to n=2).