$A$ buffer solution contains $0.1 \ M$ of acetic acid and $0.1 \ M$ of sodium acetate. What will be its $pH$,if $pK_a$ of acetic acid is $4.75$?

$pH$ 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 $mL$)? $[\log 2 = 0.3]$

Which of the following statements is incorrect for a buffer solution?

$A$ $0.15 \text{ mol}$ of pyridinium chloride is added to $500 \text{ cm}^3$ of $0.2 \text{ M}$ pyridine solution. Assuming no change in volume upon mixing, what is the $pH$ of the resulting solution? (Given: $pK_b$ of pyridine $= 8.75$)

$20$ mL of a solution of acetic acid required $28.4$ mL of $0.1$ $M$ NaOH for its neutralization. $A$ solution $(X)$ was prepared by mixing $20$ mL of the above acetic acid and $14.2$ mL of $0.1$ $M$ NaOH solution. What is the pH of the solution $(X)$? ($pK_a$ value of acetic acid is $4.75$).

$pH$ of a solution of $10 \ mL$ $1 \ N$ sodium acetate and $50 \ mL$ $2 \ N$ acetic acid $(K_a = 1.8 \times 10^{-5})$ is approximately