In a dynamic random$-$access memory $($DRAM$)$ computer chip, each memory cell chiefly consists of a capacitor for charge storage. Each of these cells represents a single binary$-$bit value of $1$ when its $25-fF$ capacitor $)=({10}^{-15}(F)$ is charged at $0\mathrm{.}6V,$ or $0$ when uncharged at $0V.($a$)$ When it is fully charged, how many excess electrons are on a cell capacitor's negative plate? $($b$)$ OMIT