A charge of 8 mC is located at the origin. The work done in taking a small charge of $-2\times {10}^{-9} C$  from a point P (0, 0, 3 cm) to a point Q (0, 4 cm, 0), via a point R (0, 6 cm, 9 cm) is:

1. 3.27 J
2. 1.27 J
3. 0.27 J
4. 2.70 J

In a hydrogen atom, the electron and proton are bound at a distance of about 0.53 Å. The potential energy of the system in eV is:
(Taking the zero of the potential energy at an infinite separation of the electron from the proton.)
1. -23.1 eV
2. 27.0 eV
3. -27.2 eV
4. 23.7 eV