Question

A sample of gaseous H- atom on absorbing photons of energy 12.75 eV / photon get excited. On dexcitation they emit radiation. The maximum number of spectral lines obtained in the emission spectrum which have no lines of Balmer series are:

• A. 2
• B. 4
• C. 3
• D. 6

Answer 1

Answer: (B)

4

In ground state electrons have energy -13.6 eV if it absorbs 12.75 eV it have energy -0.85 eV or it reaches in fourth 3rd excited state because third exicted state have energy -0.85 eV .

on de-excitation it shows given transition

1. $4\to 1$ transition

2. $4\to 2$ transition

3. $4\to 3$transition

4. $3\to 1$ transition

5. $3\to 2$ transition

6. $2\to 1$ transition

but according to question in emission spectra contains no line of Balmer series so 2nd and 5th transition is not taken and only four transition is possible