Which of the following is a buffer solution?

$2 \ g$ acetic acid and $3 \ g$ sodium acetate are present in $100 \ mL$ aqueous solution. What will be the $pH$ of the solution if the ionisation constant of acetic acid is $1.8 \times 10^{-5}$?

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 ...........

The Henderson-Hasselbalch equation for an acidic buffer is given by $pH - pK_a = 5$. This condition holds true when:

$A$ certain buffer solution contains equal concentrations of $X^-$ and $HX$. If the $K_a$ of $HX$ is $10^{-8}$,then the $pH$ of the buffer solution will be ...... .

The $pH$ of blood in the human body is maintained by $CO_2$ and $H_2CO_3$. What is this process called?