X_2( g )+ Y_2( g ) ⇌ 2 Z ( g ) X_2( g ) and Y_2( g ) are added to a 1 L flask and it is found that the system attains the above equilibrium at T ( K…

$$\mathrm{X}_2(\mathrm{~g})+\mathrm{Y}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{Z}(\mathrm{~g}) $$ $\displaystyle \mathrm{X}_2(\mathrm{~g})$ and $\displaystyle \mathrm{Y}_2(\mathrm{~g})$ are added to a $\displaystyle 1$ L flask and it is found that the system attains the above equilibrium at $\displaystyle \mathrm{T}(\mathrm{K})$ with the number of moles of $\displaystyle \mathrm{X}_2(\mathrm{~g}), \mathrm{Y}_2(\mathrm{~g})$ and $\displaystyle \mathrm{Z}(\mathrm{g})$ being $\displaystyle 3,3$ and $\displaystyle 9$ mol respectively (equilibrium moles). Under this condition of equilibrium, $\displaystyle 10$ mol of $\displaystyle \mathrm{Z}(\mathrm{g})$ is added to the flask and the temperature is maintained at $\displaystyle \mathrm{T}(\mathrm{K})$. Then the number of moles of Z(g) in the flask when the new equilibrium is established is $\displaystyle \_\_\_\_$. (Nearest integer)