The $pH$ of a buffer solution decreases by $0.02$ units when $0.12 \ g$ of acetic acid is added to $250 \ mL$ of a buffer solution of acetic acid and potassium acetate at $27^{\circ} C$. The buffer capacity of the solution is

Which one of the following pairs of solutions is not an acidic buffer?

How many $mL$ of $0.2 \, M \, KCN$ should be mixed with $200 \, mL$ of $0.1 \, M \, HCN$ so as to make a mixture of $pH = 3$ ($pK_a$ for $HCN = 6$)?

One litre buffer solution was prepared by adding $0.10 \ mol$ each of $NH_3$ and $NH_4Cl$ in deionised water. The change in $pH$ on addition of $0.05 \ mol$ of $HCl$ to the above solution is $............ \times 10^{-2}$ ($Nearest$ $integer$) ($Given$: $pK_b$ of $NH_3 = 4.745$ and $\log_{10} 3 = 0.477$)

$A$ solution of $H_3BO_3$ and borax is known as:

The $pH$ of a buffer solution prepared by mixing $50 \ mL$ of $0.2 \ M$ $CH_3COOH$ and $250 \ mL$ of $CH_3COONa$ is $4.8$. What is the concentration of $CH_3COONa$ (in $M$)? Given that the $pKa$ of $CH_3COOH$ is $4.8$.