Problem $2$:

A deuteron $-$ which is a nucleus made of $1$ proton $(p)$ and $1$ neutron $(n)-$is located between the plates of a parallel$-$plate capacitor as shown.

$[$a$]$ Calculate the mass and charge of this nucleus

$[$b$]$ Draw the electric force acting on the nucleus

$[$c$]$ How large should this force be to exactly balance the weight of the nucleus so that the nucleus remains stationary?