Question

The ratio of longest wavelength lines in the Balmer and Paschen series of hydrogen spectrum is

• A. $\frac{5}{36}$
• B. $\frac{7}{20}$
• C. $\frac{7}{144}$
• D. $\frac{5}{27}$

Answer 1

Answer: (B)

$\frac{7}{20}$

$\frac{1}{{\lambda }_B}=R[\frac{1}{2^2}-\frac{1}{3^2}]$

$\frac{1}{{\lambda }_P}=R[\frac{1}{3^2}-\frac{1}{4^2}]$

$\Rightarrow \frac{{\lambda }_B}{{\lambda }_P}=\frac{7}{20}$