In hydrogen atom the kinetic energy of electron is 3.4 eV. The distance of that electron from the nucleus

K.E of electron in H-atom = 3.4evTotal energy of electron in 2nd orbit of H-atom = -3.4 ev/atomFor 2nd orbit of H-atom Magnitude of T.E of electron =  Magnitude of K.E of electron = 3.4 ev      r2 = 0.53(22) Aº        = 2.116 Aº