$7\mathrm{.}5$ mL of a $0\mathrm{.}49$ M solution of the strong acid HCl was diluted with water to a total volume of $1000\mathrm{.}0$ mL at $25\backslash$deg C$.$ Calculate the following. $($The Kw at $25\backslash$deg C is $1\mathrm{.}011014.)$

$($a$)$ the concentration of H$3$O$+$ ions in the diluted HCl solution