Question

Consider the spectral line resulting from the transition $n=2\to n=1$ in the atoms and ions given below. The shortest wavelength is produced by

• A. hydrogen atom
• B. deuterium atom
• C. singly ionized Helium
• D. doubly ionised Lithium

Answer 1

The correct option is D doubly ionised Lithium

We know that, $\frac{1}{\lambda }=R{Z}^2[\frac{1}{n_2^2}-\frac{1}{n_1^2}]\Rightarrow \frac{1}{\lambda }\alpha Z^2$
$\lambda$ is shortest when $\frac{1}{\lambda }$ is largest i.e., when Z is big. Z is highest for lithium.