Question

If $R$ is the Rydberg Constant in $cm ^{-1}$, then hydrogen atom does not emit any radiation of wave-length in the range of

• A. $\frac{1}{R}$ to $\frac{4}{3 R} cm$
• B. $\frac{7}{5 R}$ to $\frac{19}{5 R} cm$
• C. $\frac{4}{R}$ to $\frac{36}{5 R} cm$
• D. $\frac{9}{R}$ to $\frac{144}{7 R} cm$

Answer 1

Answer: (A)

we know that
$\frac{1}{\lambda}=R\left[\frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}}\right]$
$n_{1}=1, n_{2}=2$
$\frac{1}{\lambda}=R\left[1-\frac{1}{4}\right]$
$\lambda=\frac{4 }{3 R}$ (maximum)
$n_{1}=1, n_{2}=\infty$
$\lambda=\frac{1}{R}$ (minimum)
$\frac{1}{R}$ to $\frac{4}{3 R}$