The hydrogen ion concentration of a $0.006 \ M$ benzoic acid solution is $(K_a = 6 \times 10^{-5})$

The $K_a$ of monobasic acid $A, B$ and $C$ are $10^{-6}, 10^{-8}$ and $10^{-10}$ respectively. The concentrations of $A, B$ and $C$ are respectively $0.1 \ M, 0.01 \ M$ and $0.001 \ M$. Which of the following is correct for $pOH$ of $A, B$ and $C$?

At $T$ $(K)$,if the ionisation constant of ammonia in solution is $2.5 \times 10^{-5}$,the $pH$ of $0.01 \ M$ ammonia solution and the ionisation constant of its conjugate acid respectively at that temperature are $(\log 2 = 0.30)$

It has been found that the $pH$ of a $0.01 \ M$ solution of an organic acid is $4.15$. Calculate the concentration of the anion,the ionization constant of the acid and its $pK_a$.

$1.0 \ mol$ of $HCl$ and $1.0 \ mol$ of $CH_3COONa$ are dissolved in water to make a $1 \ L$ solution. What is the concentration of $H^+$ in the solution? ($K_a$ for $CH_3COOH = 1.6 \times 10^{-5}$)

For a $10^{-3} \ M \ H_2CO_3$ solution,if the degree of dissociation $\alpha = 10\%$,what will be the value of $pH$?