Suppose the charge of a proton and an electron differ slightly. One of them is - e, the other is (e + Ae). If the net of electrostatic force and gravitational force between two hydrogen atoms placed at a distance d (much greater than atomic size) apart is zero, then Ae is of the order of [Given mass of hydrogen m = 1.67 10 kg] (a) 10 "C (c) 10 C -27 h (b) 10-37 C (d) 10-20 C