Ionisation energy of a hydrogen like ion A is greater than that of another hydrogen like ion B. Let r, u, E and L represent the radius of the orbit, speed of the electron, energy of the atom and orbital angular momentum. In ground state,
As ionisation energy is the energy needed to detach an electron from the atom, thus the electrons will gain some speed when detached from the atom and therefore ionisation energy will directly depend upon the speed of the electron
Thus, option B. will be the correct answer.
Option A. is not correct as ionisation energy does not depend upon the radius of the atom
Option C. is not correct as ionisation energy is independent of the atom energy and depends upon the energy supplied to detach the electron.
Option D. is not correct as ionisation energy is independent of angular momentum.