Suppose the charge of a proton and an eleckon differ slightly. One of them is - e, the other is $(e + \Delta e)$. 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
$\Delta_e$
is of the order of [Given mass of hydrogen $m_h= 1.67 \times 10^{27}\;kg]$
