Aqueous solutions of $HNO_{3}$, $KOH$, $CH_{3}COOH$, and $CH_{3}COONa$ of identical concentration are provided. The pair$(s)$ of solutions which form a buffer upon mixing is (are):

Calculate the molar ratio of a weak acid $HA$ $(K_a=10^{-6})$ and its salt with a strong base,so that the $pH$ of the buffer solution is $6$.

Which of the following may be added to one litre of water to act as a buffer?

$A$ certain buffer solution contains equal concentrations of $3.9 \times 10^{-5} \ M$ $X^{-}$ and $HX$. The $K_b$ for $X^{-}$ is $10^{-10}$. The $pH$ of the buffer is:

Which of the following mixtures in water acts as a basic buffer?

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 $\log_{10} 3 = 0.477$)