The stepwise formation of [ Cu ( NH_3)_4]^2+ is given below: Cu^2++ NH_3 K_1 [ Cu ( NH_3)]^2+ [ Cu ( NH_3)]^2++ NH_3 K_2 [ Cu ( NH_3)_2]^2+ [ Cu (…

The stepwise formation of $\displaystyle \left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_4\right]^{2+}$ is given below : $$\begin{aligned} & \mathrm{Cu}^{2+}+\mathrm{NH}_3 \xrightleftharpoons{\mathrm{~K}_1}\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)\right]^{2+} \\ & {\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)\right]^{2+}+\mathrm{NH}_3 \xrightleftharpoons{\mathrm{~K}_2}\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_2\right]^{2+}} \\ & {\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_2\right]^{2+}+\mathrm{NH}_3 \xrightleftharpoons{\mathrm{~K}_3}\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_3\right]^{2+}} \\ & {\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_3\right]^{2+}+\mathrm{NH}_3 \xrightleftharpoons{\mathrm{~K}_4}\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_4\right]^{2+}} \end{aligned} $$ The value of stability constants $\displaystyle \mathrm{K}_1, \mathrm{~K}_2, \mathrm{~K}_3$ and $\displaystyle \mathrm{K}_4$ are $\displaystyle 10^4, 1.58 \times 10^3, 5 \times 10^2$ and $\displaystyle 10^2$ respectively. The overall equilibrium constants for dissociation of $\displaystyle \left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_4\right]^{2+}$ is $\displaystyle x \times 10^{-12}$. The value of $\displaystyle x$ is \_\_\_\_. (Rounded off to the nearest integer)