Question

Which of the following statement is correct in connection with hydrogen spectrum

• A. The longest wavelength in the Balmer series is longer than the longest wavelength in Lyman series
• B. The shortest wavelength in the Balmer series is shorter than the shortest wavelength in the Lyman series
• C. The longest wavelength in both Balmer and Lyman series are equal
• D. The longest wavelength in Balmer series is shorter than the longest wavelength in the Lyman series.

Answer 1

The correct option is A The longest wavelength in the Balmer series is longer than the longest wavelength in Lyman series

Energy level for $H_2$ spectrum

Energy of a photon
$E=\frac{hc}{\lambda }$
$\lambda \propto \frac{1}{E}$
In lyman
${\lambda }_{\text{longest}}=\frac{hc}{E_{min}}=\frac{hc}{10.2\left(ev\right)}$
In Balmer
${\lambda }_{\text{longest}}=\frac{hc}{E_{min}}=\frac{hc}{1.89\left(eV\right)}$
${\lambda }_{\text{longest/balmer}}>{\lambda }_{\text{longest/lyman}}$
Hence, option (A) is correct.