The ionization constant $(K_a)$ of a certain weak acid is $10^{-4}$. What should be the $[salt]$ to $[acid]$ ratio if we have to prepare a buffer with $pH = 5$ using this acid and one of its salts?

The $pK_a$ of a weak acid $(HA)$ is $4.5$. The $pOH$ of an aqueous buffered solution of $HA$ in which $50\%$ of the acid is neutralized in its titration with a strong base $(BOH)$ is

The $pH$ of an acidic buffer mixture is

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 $\log_{10} 3 = 0.477$)

Which mixture forms a buffer when dissolved in $1 \, L$ of water?

The $pK_a$ of an equimolar mixture of sodium acetate and acetic acid is $4.74$. What is the $pH$ of the solution?