The ${\mathrm{OH}}^{-}$ concentration in a mixture of $5.0 \mathrm{mL}$ of $0.0504 \mathrm{M} {\mathrm{NH}}_4\mathrm{Cl}$ and $2 \mathrm{mL}$ of $0.0210 \mathrm{M} {\mathrm{NH}}_3$ solution is $x\times {10}^{-6} \mathrm{M}$. The value of $x$ is (Nearest integer) [Given $K_w=1\times {10}^{-14}$ and $\left.K_b=1.8\times {10}^{-5}\right]$

For the reaction

$\mathrm{A}+\mathrm{B}\rightleftharpoons 2\mathrm{C}$

the value of equilibrium constant is $100$ at $298 \mathrm{K}$. If the initial concentration of all the three species is $1 \mathrm{M}$ each, then the equilibrium concentration of $\mathrm{C}$ is $\mathrm{x}\times {10}^{-1} \mathrm{M}$. The value of $\mathrm{x}$ is _______. (Nearest integer)

[Given $\sqrt{2}=1.41$]

The stepwise formation of ${\left[\mathrm{Cu}{\left({\mathrm{NH}}_3\right)}_4\right]}^{2+}$ is given below:

${\mathrm{Cu}}^{2+}+{\mathrm{NH}}_3\stackrel{{\mathrm{K}}_1}{\rightleftharpoons }{\left[\mathrm{Cu}\left({\mathrm{NH}}_3\right)\right]}^{2+}$

${\left[\mathrm{Cu}\left({\mathrm{NH}}_3\right)\right]}^{2+}+{\mathrm{NH}}_3\stackrel{{\mathrm{K}}_2}{\rightleftharpoons }{\left[\mathrm{Cu}{\left({\mathrm{NH}}_3\right)}_2\right]}^{2+}$

${\left[\mathrm{Cu}{\left({\mathrm{NH}}_3\right)}_2\right]}^{2+}+{\mathrm{NH}}_3\stackrel{{\mathrm{K}}_3}{\rightleftharpoons }{\left[\mathrm{Cu}{\left({\mathrm{NH}}_3\right)}_3\right]}^{2+}$

${\left[\mathrm{Cu}{\left({\mathrm{NH}}_3\right)}_3\right]}^{2+}+{\mathrm{NH}}_3\stackrel{{\mathrm{K}}_4}{\rightleftharpoons }{\left[\mathrm{Cu}{\left({\mathrm{NH}}_3\right)}_4\right]}^{2+}$

The value of stability constants ${\mathrm{K}}_1, {\mathrm{K}}_2, {\mathrm{K}}_3$ and ${\mathrm{K}}_4$ are ${10}^4, 1.58\times {10}^3, 5\times {10}^2$ and ${10}^2$ respectively. The overall equilibrium constants for dissociation of ${\left[\mathrm{Cu}{\left({\mathrm{NH}}_3\right)}_4\right]}^{2+}$ is $x\times {10}^{-12}.$ The value of $\mathrm{x}$ is _____ (Rounded off to the nearest integer)