Buffer system helps to maintain blood $pH$ between .......

The $pH$ of a solution containing $0.10 \ M$ sodium acetate and $0.03 \ M$ acetic acid $(pK_a = 4.57)$ at $298 \ K$ will be ...........

What is the $OH^-$ ion concentration of a solution containing $0.05 \, M$ ammonium hydroxide and $0.001 \, M$ ammonium chloride? Given $K_b(NH_4OH) = 1.8 \times 10^{-5}$.

$A$ solution is prepared by mixing $0.01 \ mol$ each of $H_2CO_3$,$NaHCO_3$,$Na_2CO_3$,and $NaOH$ in $100 \ mL$ of water. The $pH$ of the resulting solution is. . . . . . .
[Given : $pK_{a1}$ and $pK_{a2}$ of $H_2CO_3$ are $6.37$ and $10.32$,respectively; $\log 2=0.30$ ]

$1 \, M$ $NaCl$ and $1 \, M$ $HCl$ are present in an aqueous solution. The solution is:

$A$ buffer solution can be prepared from a mixture of