The $pK_a$ of $HCN$ is $9.30$. What is the $pH$ of a solution prepared by mixing $2.5 \ mol$ of $KCN$ and $2.5 \ mol$ of $HCN$ in $500 \ mL$ of water (in $.30$)?

The $pOH$ of a basic buffer (e.g.,$NH_4OH/NH_4Cl$) is $5$. If the concentration of the salt is tripled while the concentration of the base remains constant,find the new $pOH$ value. (Given: $\log 3 = 0.48$)

For preparing a buffer solution of $pH = 5$ by mixing sodium acetate and acetic acid,the ratio of the concentration of salt and acid should be $(K_a = 10^{-5})$:-

$A$ buffer solution contains $0.1 \ mol$ of sodium acetate dissolved in $1000 \ cm^{3}$ of $0.1 \ M$ acetic acid. To the above buffer solution,$0.1 \ mol$ of sodium acetate is further added and dissolved. The $pH$ of the resulting buffer is

Derive the equation for the calculation of $pH$ of an acidic buffer solution.

Which of the following does not act as a buffer solution?