The ionisation potential of hydrogen atom is $$13.6\ eV$$. The energy required to remove an electrons in the $$n=2$$ state of hydrogen atom is:
Correct option is D. $$3.4\ eV$$
$$E_n=-13.6\ ev\left (\dfrac {Z^2}{n^2}\right)=\dfrac {-E_1}{n^2}[I.E_1 =-E_1 =13.6\ eV \Rightarrow E_1=-13.6\ eV]$$
$$\therefore E_2 =\dfrac {-13.6\ ev}{4}=-3.4ev$$
$$\therefore I.E_2=-E_2 =3.4\ ev$$.
Option D is correct.