The $pK_a$ of a weak acid $(HA)$ is $4.5$. The $pOH$ of an aqueous buffer solution of $HA$ in which $50\%$ of the acid is ionized is

The dissociation constant of a weak acid is $1 \times 10^{-4}.$ In order to prepare a buffer solution with a $pH = 5,$ the $[Salt]/[Acid]$ ratio should be

$A$ buffer solution is prepared by mixing equimolar acetic acid and sodium acetate. If $K_{a}$ of acetic acid is $1.78 \times 10^{-5}$,find the $pH$ of the buffer solution.

The $K_b$ of $NH_4OH$ is $1.8 \times 10^{-5}$. Calculate the $pH$ of a solution containing $0.15 \ M$ $NH_4OH$ and $0.25 \ M$ $NH_4Cl$.

Which of the following mixtures gives a buffer solution with $pH = 9.25$?
Given: $pK_{b} (NH_{4}OH) = 4.75$

$A$ 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: $K_b = 2 \times 10^{-5}$]