Question

If photons of energy $12.75eV$ are passing through hydrogen gas in ground state then no of lines in emission spectrum will be

• A. $6$
• B. $4$
• C. $3$
• D. $2$

Answer 1

Answer: (A)

$6$

$\begin{array}{c}\text{Given- * Energy of photons}=12.75eV\\ \Rightarrow \text{Let the state of electron initially be}{n}^{\text{th}}\text{state.}\\ \begin{array}{cc}\Rightarrow 12.75=& 13.6[\frac{1}{1}-\frac{1}{n^2}]\\ & \Rightarrow n=4\\ \text{No. of Spectral lines}& =\frac{n(n-1)}{2}=6\end{array}\end{array}$