The acidic buffer $(HX + NaX)$ can be best used to maintain the $pH$ in the range $(4 - 6)$. Find the $pK_b$ of $X^-$.

When $NaOH$ is added to a $CH_3COOH$ solution,$60\%$ of the acid is neutralized. If the $pK_a$ is $4.7$,the $pH$ of the resulting solution is:

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

Which of the following cannot act as a buffer solution?

For a weak acid $(HA)$,$pK_a = 4.5$. The $pOH$ of a buffer solution of $HA$ in which $50\%$ of the acid is ionized is:

Equal volumes of $0.5 \ N$ acetic acid and $0.5 \ N$ sodium acetate are mixed. What is the $pH$ of the resultant solution? $(pK_{a}$ of acetic acid $= 4.75)$