$15\mathrm{.}41$ The following resistances are observed at $25C$ in a

conductivity cell filled with various solutions: $411\mathrm{.}82$ for a

$0\mathrm{.}741913wt\%KCl$ solution; $10\mathrm{.}875k$ for a $0\mathrm{.}001000mo\frac{l}{d}{m}^3$

solution of $MC{l}_2$;$368\mathrm{.}0k$ for the deionized water used to pre$-$

pare the solutions. The conductivity of a $0\mathrm{.}741913\%KCl$ solu$-$

tion is known to be $0\mathrm{.}012856($U$.$S$.$ int. $$ at $25C.$ The

U$.$S$.$ international ohm is an obsolete unit equal to $1\mathrm{.}000495.$

Calculate $($a$)$ the cell constant: $(b)$ of $MC{l}_2$ in a $25C$ aqueous

${10}^{-3}mo\frac{l}{d}{m}^3$ solution; $($c$){}_m$ of $MC{l}_2$ in this solution; $(d){}_{eq}$

of $MC{l}_2$ in this solution.