The $pH$ at which the maximum hydrate is present in a solution of oxaloacetic acid $(HOOC-CO-CH_2-COOH)$ with $pK_{a1} = 2.2$ and $pK_{a2} = 3.98$ is:

$A$ $0.1 \ N$ solution of an acid at room temperature has a degree of ionisation $0.1$. The concentration of $OH^{-}$ would be

Which of the following statement$(s)$ is/are correct?
$ (A) $ The $pH$ of $1 \times 10^{-8} \ M \ HCl$ solution is $8$.
$ (B) $ The conjugate base of $H_2PO_4^{-}$ is $HPO_4^{2-}$.
$ (C) $ $K_w$ increases with increase in temperature.
$ (D) $ When a solution of weak monoprotic acid is titrated against a strong base at half neutralisation point,$pH = pK_a$.
Choose the correct answer from the option given below.

The solubility of $AgCl$ is $4 \times 10^{-6} \ M$. Find its $K_{sp}$. Also,find its new solubility in the presence of $2 \times 10^{-3} \ M \ CaCl_2$.

Assign $A, B, C, D$ from the given type of reaction.
$Zn(OH)_2 \downarrow + 2NaOH \longrightarrow Na_2ZnO_2 + 2H_2O$

The $pH$ of a solution obtained by mixing $50 \, mL$ of $1 \, M \, HCl$ and $30 \, mL$ of $1 \, M \, NaOH$ is $x \times 10^{-4}$. The value of $x$ is ...... . (Nearest integer) $[\log 2.5 = 0.3979]$