Key Idea : Search for the relations of electric potential and electric field at a particular point. At any point, electric potential due to charge $Q$ is
$V=\frac{1}{4 \pi \varepsilon_0} \cdot \frac{Q}{r}$
where $r$ is the distance of observation point from the charge.
At the same point, electric field is
$E=\frac{1}{4 \pi \varepsilon_0} \cdot \frac{Q}{r^2}$
Combining Eqs. (i) and (ii), we have
$\begin{aligned}
E & =\frac{4 \pi \varepsilon_0 V^2}{Q}=\frac{4 \pi \varepsilon_0 \times\left(Q \times 10^{11}\right)^2}{Q} \\
& =4 \pi \varepsilon_0 \mathrm{Q} \times 10^{22} \mathrm{~V} / \mathrm{m}
\end{aligned}$