(a) Given: The total energy of an electron in the first excited state of the hydrogen atom is about –3.4 eV.

Kinetic energy of the electron in this state = negative of the total energy = -E

Kinetic energy of the electron in this state =-(-3.4)eV = + 3.4 eV

(b) Potential energy is given as the negative of the twice of the kinetic energy

U = -2 (3.4) eV

U = -6.8eV

(c) If the choice of the zero of potential energy is changed, then the value of potential energy of the system also changes and as we know the total energy is sum of kinetic energy as well as potential energy. Therefore, the potential energy will also changes.