Why is the following anionic hydrolysis correct?
$X^{-} + H_2O \rightleftharpoons HX + OH^{-}$

The ionization constant of nitrous acid is $4.5 \times 10^{-4}$. Calculate the $pH$ of $0.04 \ M$ sodium nitrite solution and also its degree of hydrolysis.

Explain the following with reasons:
$(i)$ $NaCl$ solution is neutral. The solution of strong acid and strong base salts is neutral.
$(ii)$ $NaCH_3COO$ solution is basic. The solution of strong base and weak acid salt is basic.
$(iii)$ $NH_4Cl$ solution is acidic. The solution of weak base and strong acid salt is acidic.
$(iv)$ The solution of $NH_4CH_3COO$ is (almost) neutral. The solution of weak acid - weak base salts is almost neutral.

For a weak acid $HA$,$pK_a = 4.80$. For a weak base $BOH$,$pK_b = 4.78$. What is the $pH$ of an aqueous solution of the salt $BA$?

The approximate $pH$ of $0.01 \ M \ NaHA$ is calculated by: ($K_{a_1} = 10^{-6}$ and $K_{a_2} = 10^{-8}$ are ionization constants of $H_2A$)

An aqueous solution of ammonium carbonate is