Ch$23$ Capacitors in Combination: A $10\mathrm{.}0-F$ capacitor and a $30\mathrm{.}0-F$ capacitor are connected in series across a $12-$V potential source. What is the potential difference across the $10\mathrm{.}0-F$ capacitor?

$9\mathrm{.}0$ V

$7\mathrm{.}0$ V

$4\mathrm{.}6$ V

$8\mathrm{.}2$ V