For the circuit shown in the figure below, $C=4\mathrm{.}50F,E=120V,$ and $R=350.$ After having been at contact a for a long time, the switch throw is rotated to contact $b.$ How much charge is on the upper plate of the capacitor $7\mathrm{.}50$ ms after the switch throw is rotated to contact $b?$

$540C$

$4\mathrm{.}62C$

$1\mathrm{.}58C$

$0\mathrm{.}343C$