$\mathrm{Mg}{\left(\mathrm{OH}\right)}_2$ is precipitated when $\mathrm{NaOH}$ is added to a solution of ${\mathrm{Mg}}^{2+}$. If the final concentration of ${\mathrm{Mg}}^{2+}$ is ${10}^{-10} \mathrm{M}$, the concentration of ${\mathrm{OH}}^{-}\left(\mathrm{M}\right)$ in the solution is

[Solubility product for $\mathrm{Mg}{\left(\mathrm{OH}\right)}_2=5.6\times {10}^{-12}$]

$\mathrm{NiO}$ is to be reduced to $\mathrm{Ni}$ in an industrial process by the use of the reaction $\mathrm{NiO} \left(\mathrm{s}\right)+\mathrm{CO} \left(\mathrm{g}\right)\rightleftharpoons \mathrm{Ni} \left(\mathrm{s}\right)+{\mathrm{CO}}_2 \left(\mathrm{g}\right)$

At $1600 \mathrm{K}$, the equilibrium constant for the reaction is $600$. If a $\mathrm{CO}$ pressure of $150 \mathrm{mm} \mathrm{Hg}$ is to be employed in the furnace and the total pressure never exceeds $760 \mathrm{mm} \mathrm{Hg},$ will the reduction occur?

Aqueous solutions of ${\mathrm{HNO}}_3$, $\mathrm{KOH}$, ${\mathrm{CH}}_3\mathrm{COOH}$ and ${\mathrm{CH}}_3\mathrm{COONa}$ of identical concentrations are provided. The pair(s) of solutions which form a buffer upon mixing is (are):

At $25°\mathrm{C}$, the solubility product of $\mathrm{Mg}(\mathrm{OH}{)}_2$ is $1.0\times {10}^{-11}$. At what $\mathrm{pH}$, will ${\mathrm{Mg}}^{2+}$ ions start precipitating in the form of $\mathrm{Mg}(\mathrm{OH}{)}_2$ from a solution of $0.001 \mathrm{M} {\mathrm{Mg}}^{2+}$ ions?

$\text{[Hint: Calculate} \left[{\mathrm{OH}}^{-}\right] \text{from} {\mathrm{K}}_{\mathrm{sp}}=\left[{\mathrm{Mg}}^{2+}\right]{\left[{\mathrm{OH}}^{-}\right]}^2\text{]}$

Solubility product of $\mathrm{AgBr}$ is $5.0\times {10}^{-13}$. The quantity of $\mathrm{KBr} (\mathrm{mol}.\mathrm{wt}.=120)$ to be added to $1$ litre of $0.05 \mathrm{M}$ solution of ${\mathrm{AgNO}}_3$ to start the precipitation of $\mathrm{AgBr}$ is:

$[\mathrm{Hint}: \mathrm{Wt}. \mathrm{in} \mathrm{g}= \mathrm{no}. \mathrm{of} \mathrm{moles} \times \mathrm{mol}. \mathrm{wt}.]$