Hydrolysis of salts

On decreasing the $p\mathrm{H}$ from 7 to 2, the solubility of a sparingly soluble salt (MX) of a weak acid (HX) increased from $10^{-4}\,\mathrm{mol\,L^{-1}}$ to $10^{-3}\,\mathrm{mol\,L^{-1}}$. The $pK_\mathrm{a}$ of HX is

20 mL of 0.1 M $\mathrm{NH_4OH}$ is mixed with 40 mL of 0.05 M HCl. The pH of the mixture is nearest to :

(Given : $K_b(\mathrm{NH_4OH})=1\times10^{-5}$, log 2 = 0.30, log 3 = 0.48, log 5 = 0.69, log 7 = 0.84, log 11 = 1.04)

The solubility of a salt of weak acid (AB) at pH 3 is $\mathbf Y\times10^{-3}$ mol L⁻¹. The value of Y is ______.

(Given that the value of solubility product of AB ($K_{sp}$) = $2\times10^{-10}$ and the value of ionization constant of HB ($K_a$) = $1\times10^{-8}$)

Dilution processes of different aqueous solutions, with water, are given in LIST-I. The effects of dilution of the solutions on $[\mathrm{H^+}]$ are given in LIST-II.

(Note: Degree of dissociation ($\alpha$) of weak acid and weak base is $\ll 1$; degree of hydrolysis of salt $\ll 1$; $[\mathrm{H^+}]$ represents the concentration of $\mathrm{H^+}$ ions)

Match each process given in LIST-I with one or more effect(s) in LIST-II. The correct option is

p$K_a$ of a weak acid (HA) and p$K_b$ of a weak base (BOH) are 3.2 and 3.4, respectively. The pH of their salt (AB) solution is :

Assuming that the degree of hydrolysis is small, the pH of 0.1 M solution of sodium acetate ($K_a=1.0\times10^{-5}$) will be :

Amongst the following, the total number of compounds whose aqueous solution turns red litmus paper blue is

KCN, $\ce{K2SO4}$, $\ce{(NH4)2C2O4}$, NaCl, $\ce{Zn(NO3)2}$, $\ce{FeCl3}$, $\ce{K2CO3}$, $\ce{NH4NO3}$, LiCN

The dissociation constant of a substituted benzoic acid at 25°C is $1.0\times10^{-4}$. The pH of a 0.01 M solution of its sodium salt is

2.5 mL of $\frac25$ M weak monoacidic base ($K_b=1\times10^{-12}$ at 25 °C) is titrated with $\frac2{15}$ M HCl in water at 25 °C. The concentration of H⁺ at equivalence point is ($K_w=1\times10^{-14}$ at 25 °C)