Question

The minimum energy (numerical value) required to be supplied to H-atom to push its electron from 2nd orbit to the 3rd orbit is:

• A. 1.9 eV
• B. 2.2 eV
• C. 2.7 eV
• D. 7.0 eV

Answer 1

The correct option is A 1.9 eV

$\Delta E=13.6eV\times (1/n_1^2-1/n_2^2)$
For electron transition from $n=2$ to $n=3$, put $n_1=2$ and $n_2=3$ to get $\Delta E=1.89eV\approx 1.9eV$.