$pH$ of a mixture of $1 \ M$ benzoic acid $(pK_a = 4.20)$ and $1 \ M$ $C_6H_5COONa$ is $4.5$. What is the volume of benzoic acid required to prepare a $300 \ mL$ buffer solution (in $mL$)? $[\log 2 = 0.3]$

All the given solutions have the same concentration. Mixing equal volumes of which of the following will produce a buffer solution?
$A = NH_4Cl$; $B = CH_3COONa$; $C = NH_4OH$; $D = CH_3COOH$

$A$ buffer solution is prepared by mixing $0.2 \ M$ sodium acetate and $0.1 \ M$ acetic acid. If $pK_{a}$ for acetic acid is $4.7$,find the $pH$.

Which of the following is a buffer solution?

The $pH$ of blood is maintained by a proper balance of $H_2CO_3$ and $NaHCO_3$ concentrations. What volume of $5 \, M \, NaHCO_3$ solution should be mixed with $10 \, mL$ of $2 \, M \, H_2CO_3$ to maintain a $pH$ of $7.4$ (in $, mL$)? (Given: $K_a$ for $H_2CO_3 = 7.8 \times 10^{-7}$)

The $pH$ of a simple sodium acetate buffer is given by $pH = pK_a + \log \frac{[Salt]}{[Acid]}$. $K_a$ of acetic acid $= 1.8 \times 10^{-5}$. If $[Salt] = [Acid] = 0.1 \, M$,the $pH$ of the solution would be about