How much work must be done to pull apart the electron and the proton that make up the hydrogen atom, if the atom is initially in the state n = 2?

The electrostatic P.E. is zero when the electron and proton are far apart from each other. Work done in pulling electron and proton far away from each otherW=Ef−Ei=0−Ei=−−13.6n2eV⇒W=13.6(2)2×1.6×10−19J=3.4×1.6×10−19J