Question

If the shortest wavelength in Lyman series of hydrogen atom is $A$, then the longest wavelength in Paschen series of $He^{+}$ is :

• A. $\frac{5A}{9}$
• B. $\frac{9A}{5}$
• C. $\frac{36A}{5}$
• D. $\frac{36A}{7}$

Answer 1

Answer: (D)

$\frac{36A}{7}$

Answer 2

Shortest wavelength is corresponding to best ine
? n = 1 (Lyman series)
n = 8 (infinite)
\frac{1}{A}=r\times\left(1\right)^{2}\left\\{\frac{1}{12}-\frac{1}{2}\right\\}=R
Longest wavelength = 1 Line
? = 3 n = 4
\frac{1}{\lambda}=r\times\left(2\right)^{2}\left\\{\frac{1}{3^{2}}-\frac{1}{4^{2}}\right\\}=\frac{r\times7}{36}
$\lambda=\frac{36A}{7}$