The Bohr model of the hydrogen atom states that the single electron can exist only in certain allowed orbits around the proton. The radius of each Bohr orbit is $r=n^{2}(0.0529 \mathrm{nm})$ where $n=1,2,3, \ldots .$ Calculate the electric potential energy of a hydrogen atom when the electron is in the (a) first allowed orbit, with $n=1 ;$ (b) second allowed orbit, with $n=2 ;$ and (c) when the electron has escaped from the atom, with $r=\infty$. Express your answers in electron volts.