Question

Hydrogen atom in its ground state is excited by radiation of wavelength $975\stackrel{\circ }{A}$. How many lines will be there in
the emission spectrum

• A. 2
• B. 4
• C. 6
• D. 8

Answer 1

The correct option is C 6

Using $\frac{1}{\lambda }=R[\frac{1}{n_1^2}-\frac{1}{n_2^2}]\Rightarrow \frac{1}{975\times {10}^{-10}}=1.097\times {10}^7(\frac{1}{1^2}-\frac{1}{n^2})\Rightarrow n=4$
Now number of spectral lines $N=\frac{n(n-1)}{2}=\frac{4(4-1)}{2}=6$