1) How many emission spectral lines are possible when a hydrogen atom is excited to nth energy level? A) $\frac{n(n+1)}{2}$ B) $\frac{(n+1)}{2}$ C) $\frac{(n-1)n}{2}$ D) $\frac{n^{2}}{4}$ Answer: Option CExplanation:number of spectral lines= $\frac{n(n-1)}{2}$ n is the oribital in which the electron exist
