At $25 \, ^\circ C$,the dissociation constant of pure water is equal to .......

$A$ sample of $MgCO_3$ is dissolved in dil. $HCl$ and the solution is neutralized with ammonia and buffered with $NH_4Cl / NH_4OH$. Disodium hydrogen phosphate reagent is added to the resulting solution. $A$ white precipitate is formed. What is the formula of the precipitate?

Assign $A, B, C, D$ for the given type of reaction:
$Mg(OH)_2 \downarrow + 2HCl \longrightarrow MgCl_2 + 2H_2O$

In a saturated solution of $Mg(OH)_2$,the degree of dissociation of $Mg(OH)_2$ is $\alpha$. Find the concentration $(C)$ of $Mg(OH)_2$ if the concentration of $[OH^{-}]$ is $2$.

What is the $pH$ of the resulting solution when $20 \text{ mL}$ of $\frac{M}{10} \text{ NaOH}$ and $10 \text{ mL}$ of $\frac{M}{10} \text{ H}_2\text{SO}_4$ are mixed together?

The $p^H$ of a mixture containing $10 \ mL$ of $0.1 \ N$ $NaOH$ and $10 \ mL$ of $0.05 \ N$ $H_2SO_4$ is ............