A certain transition in H spectrum from an excited state to ground state in one or more steps gives rise to total 10 lines. How many of these belong to uv spectrum?

Number of spectral lines when electronic transition from higher energy level to ground state $\frac{\mathrm{n}(\mathrm{n}-1)}{2}$ =10

n²-n =20

n²-n -20 =0

n² -5n +4n -20=0

(n-5) (n+4) =0

So n=5

For uv spectrum line has to come form higher level to n = 1