Consider the following reactions : $$ \begin{aligned} & \mathrm{NaCl}+\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7+\mathrm{H}_2 \mathrm{SO}_4 \rightarrow \mathrm{~A}+\mathrm{KHSO}_4+\mathrm{NaHSO}_4+\mathrm{H}_2 \mathrm{O} \\ & \mathrm{~A}+\mathrm{NaOH} \rightarrow \mathrm{~B}+\mathrm{NaCl}+\mathrm{H}_2 \mathrm{O} \\ & \mathrm{~B}+\mathrm{H}_2 \mathrm{SO}_4+\mathrm{H}_2 \mathrm{O}_2 \rightarrow \mathrm{C}+\mathrm{Na}_2 \mathrm{SO}_4+\mathrm{H}_2 \mathrm{O} \end{aligned} $$ In the product ' C ', ' X ' is the number of $O_2^{2-}$ units, ' Y ' is the total number oxygen atoms present and ' Z ' is the oxidation state of Cr . The value of $\mathrm{X}+\mathrm{Y}+\mathrm{Z}$ is $\_\_\_\_$ .