Chlorine can be prepared in the laboratory by the reaction of manganese dioxide with hydrochloric acid, $HCl(aq),$ as described by the chemical equation

$Mn{O}_2(s)+4HCl(aq)longrightarrowMnC{l}_2(aq)+2H_{2}O(l)+C{l}_2(g)$

How much $Mn{O}_2($s$)$ should be added to excess $HCl(aq)$ to obtain $125mLCl(g)$ at $25C$ and $765$ Torr?

mass of $Mn{O}_2$ :