Number of spectral lines obtained in $$He^+$$ spectra, when an electron makes transition from fifth excited state to first excited state will be

In He$$^+$$, transition from 5th excited state (n = 6) to first excited state (n = 2).

Number of spectral lines from transitions between levels n = 6 to n = 2:

Number of levels involved = 6 - 2 + 1 = 5 (levels 2, 3, 4, 5, 6).

Number of spectral lines = $$\frac{n(n-1)}{2} = \frac{5 \times 4}{2} = 10$$.

Therefore, the answer is $$\boxed{10}$$.