Correct option (b) 13.6 eV
Explanation:
The ionization energy of hydrogen in its ground state is 13.6 eV
For a hydrogen atom, composed of an orbiting electron bound to a nucleus of one proton, an ionization energy of 2.18 × 10−18 joule (13.6 electron volts) is required to force the electron from its lowest energy level entirely out of the atom.