The $[HCO_{3}^{-}]/[H_{2}CO_{3}]$ ratio in the buffer present in blood $(pH = 7.4)$ is approximately $(pK_{a} = 6.1$ for $H_{2}CO_{3})$.

The dissociation constant of $HCN$ is $5 \times 10^{-10}$. The $pH$ of the solution prepared by mixing $1.5 \, mole$ of $HCN$ and $0.15 \, mole$ of $KCN$ in water and making up the total volume to $0.5 \, dm^3$ is (in $.302$)

The $pH$ of a solution at $25\,^oC$ containing $0.10\,M$ sodium acetate and $0.03\,M$ acetic acid is ($pK_a$ for $CH_3COOH = 4.57$)

What is the $pH$ of a solution containing $50 \ mL$ each of $0.1 \ M$ sodium acetate and $0.01 \ M$ acetic acid (in $.5$)? $(pK_{a} \ CH_3COOH = 4.50)$

Which of the following is not a buffer solution?

$A$ solution contains $0.2 \ M \ NH_4OH$ and $0.2 \ M \ NH_4Cl$. If $1.0 \ mL$ of $0.001 \ M \ HCl$ is added,what will be the $[OH^-]$ of the resulting solution? [Given: $K_b = 2 \times 10^{-5}$]