What the min E needed to ionize an H atom in the n=2 energy state?

Question

What the min E needed to ionize an H atom in the n=2 energy state?

Answer 1

the 1st energy level is 13.6eV and the energy levels follow the inverse square law thereafter

E(n) = 13.6/n²

so

E(2) = 13.6/2² = 3.4eV

,.,

Answer 2

Ef - Fi = (0.0eV - -3.4eV)

          = 3.4eV