Option 1 states that the ionization energy of a hydrogen atom in the ground state is 13-6 MeV. This is incorrect. MeV stands for mega-electron volts, which is a unit of energy typically used in nuclear physics. The ionization energy of an atom is usually expressed in electron volts (eV), not MeV.

Option 3 suggests that the ionization energy of a hydrogen atom in the ground state is 13-6 Joule. This is also incorrect because joule is not the commonly used unit for measuring ionization energy. Ionization energy is typically measured in electron volts (eV) or kilojoules per mole (kJ/mol), not joules.

Option 4 states that the ionization energy of a hydrogen atom in the ground state is zero. This is incorrect as well. The ionization energy of a hydrogen atom is not zero, as it requires energy to remove an electron from an atom.

Option 2 is correct. It states that the ionization energy of a hydrogen atom in the ground state is 13-6 eV. This means that it requires an energy of 13.6 electron volts to remove an electron from a hydrogen atom in its ground state. This is a well-established value and