A diatomic molecule has dipole moment of $1.2D$. If its bond length is $1{ \mathrm{A}}^0$, the fraction of electronic charge that exists on each atom is

Given , p = 1.2D and l = 1 A

We know that Dipole moment, $\mu =q\times d$
Substitute the given values in the above equation.
$1.2\times {10}^{-18}=\mathrm{q}\times {10}^{-8} \mathrm{cm}$
$q=\frac{1.2\times {10}^{-18}}{{10}^8}=1.2\times {10}^{-10}$

Charge on each atom $=\frac{\mathrm{q}}{\mathrm{e}}=\frac{1.2\times {10}^{-10}}{4.8\times {10}^{-10}}=0.25$