Question

$2s\stackrel{I}{\to }2p\stackrel{II}{\to }3d\stackrel{III}{\to }3p\stackrel{IV}{\to }4s\stackrel{V}{\to }2p$
The electronic transitions show above are observed when lithium atoms are sprayed into a hot flame. The various transitions are numbered for identification. Which of these transitions would result in emission of electromagnetic radiation (light)?

• A. I and II only
• B. I and III only
• C. I and V only
• D. III and IV only
• E. III and V only

Answer 1

The correct option is A I and II only

$\frac{1}{{\lambda }_{II}}=10976800Z^2(\frac{1}{2^2}-\frac{1}{3^2})m$

$\Rightarrow {\lambda }_{II}=72.8nm$, which lies in the range of electromagnetic radiation.

Any of the other options except $\left(A\right)$ does not contain $II$, hence by elimination, option $\left(A\right)$ is correct.