Energy of an electron in the `n^(th)` orbit of hydrogen atom is given by `E_(n) = - (13.6)/(n^2) eV`.
How much energy is required to take an electron from i:he ground state to the first excited state?

Explanation

Energy of an electron in `n^(th)`horbit of hydrogen atom is `E_n = (-13.6)/n^2 eV`
Energy of electron in ground state,
`E_1 = (-13.6)/((1)^2)`
`rArr E_1 = -13.6 eV`
Energy of electron in first excited state,
(i.e. n = 2) `E_2 = (-13.6)/((2)^2) = (-13.6)/4`
`= -3.4eV`
Thus, energy required ` = E_2 - E_1`
` = -3.4 - (13.6)`
` = - 3.4 + 13.6`
`=10.2 eV`