Question

The wavelength (in $\stackrel{o}{A}$) of an emission line obtained for $L{i}^{2+}$ during an electronic transition $n_2=2$ and $n=1$ is (R = Rydberg constant)

• A. $\frac{3R}{4}$
• B. $\frac{27R}{4}$
• C. $\frac{4}{3R}$
• D. $\frac{4}{27R}$

Answer 1

The correct option is D $\frac{4}{27R}$

By using formula,
$\overline{v}=R(\frac{1}{n_1^2}-\frac{1}{n_2^2})Z^2=R(\frac{1}{1^2}-\frac{1}{2^2})\times 3^2=R\left[\frac{4-1}{4}\right]\times 3^2=\frac{27R}{4}\therefore \lambda =\frac{1}{\overline{v}}=\frac{4}{27R}$
Here R is Rydberg constant.