A diatomic molecule has a dipole moment of $1.2\mathrm{D}$. If the bond distance is $1{ \mathrm{A}}^0$, what percentage of electronic charge (e) exists on each atom ?

Let the electronic charge on each atom be x. The dipole moment is $1.2\mathrm{D}$
We know, $1\mathrm{D}={10}^{-18}$esu.cm
The dipole moment in esu $\mathrm{cm}$ units is $1.2\times {10}^{-18}$ esu.cm
The dipole moment is the product of its charge and the inter atomic distance.
It would be $\mathrm{x}\times 100\times {10}^{-10}=1.2\times {10}^{-18}$
$\mathrm{x}=1.2\times {10}^{-10}\text{ esu }$
But the electronic charge e $=4.8\times {10}^{-10}$ esu
Partial electronic charge on each atom$=\frac{1.2\times {10}^{-10}\mathrm{esu}}{4.8\times {10}^{-10}\mathrm{esu}}\times 100$
$\mathrm{x}=25\%\text{ of }\mathrm{e}$

Hence, the correct option is option (C) 25% of e.