In a polar molecule, the ionic charge is $4.8 x {10}^{-10}$ e.s.u. If the inter ionic distance is one A^o unit. then the dipole moment is

Given ionic charge $=4.8\times {10}^{-10}$ e.s.u. and ionic distance $=1{\mathrm{A}}^{\circ }={10}^{-8}\mathrm{cm}$ we know that 

dipole moment $=$ionic charge $x$ ionic distance $=4.8 x {10}^{-10}x {10}^{-8}$

$=4.8\times {10}^{-10}$ e.s.u per $cm=4.8 debye.$