Observed dipole moment and bond length of four gaseous diatomic molecules are: P ($3.5\mathrm{D}$, $100\mathrm{pm}$), Q ($9.2\mathrm{D}$, $400\mathrm{pm}$), R ($1.80\mathrm{D}$, $92\mathrm{pm}$), S ($0.82\mathrm{D}$, $141\mathrm{pm}$). Take percent ionic character $=100\times {\mu }_{obs}/{\mu }_{ionic}$ with ${\mu }_{ionic}=ed$, $e=1.6\times 10^{-19}\mathrm{C}$ and $1\mathrm{D}=3.336\times 10^{-30}\mathrm{C}\mathrm{m}$. Which molecule has the highest percent ionic character?

1. A$\mathrm{S}$
2. B$\mathrm{P}$
3. C$\mathrm{Q}$
4. D$\mathrm{R}$