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 ...........

What is the $pH$ of the solution obtained by mixing $5.076 \ g$ of methyl ammonium nitrate $(CH_3NH_3NO_3)$ into $120 \ mL$ of $0.225 \ M$ methylamine $(CH_3NH_2$; $K_b = 4 \times 10^{-4})$?

When $1.0 \ mL$ of dilute $HCl$ acid is added to $100 \ mL$ of a buffer solution with $pH = 4.0$,what will be the resulting $pH$ of the solution?

Which among the following pairs constitutes a buffer?

$A$ student needs to prepare a buffer solution of propanoic acid and its sodium salt with $pH$ $4$. The ratio of $\frac{[CH_{3}CH_{2}COO^{-}]}{[CH_{3}CH_{2}COOH]}$ required to make the buffer is .....
Given: $K_{a}(CH_{3}CH_{2}COOH) = 1.3 \times 10^{-5}$

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 $HCN = 6$)?