At a constant temperature,the $pK_b$ of $NH_4OH$ is $4.74$. What is the $pH$ of a basic buffer containing equimolar concentrations of $NH_4OH$ and $NH_4Cl$?

Calculate $[H^{+}]$ of $0.2 \ M$ $HCN$ in $1 \ M$ $KCN$ solution. Given $K_{a(HCN)} = 4 \times 10^{-10}$.

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 would produce a buffer solution when mixed in equal volumes?

The $OH^{-}$ concentration in a mixture of $5.0 \ mL$ of $0.0504 \ M \ NH_{4}Cl$ and $2 \ mL$ of $0.0210 \ M \ NH_{3}$ solution is $x \times 10^{-6} \ M$. The value of $x$ is ..... .
(Nearest integer)
$[ \text{Given } K_{w}=1 \times 10^{-14} \text{ and } K_{b}=1.8 \times 10^{-5} ]$

Which one of the following pairs of solutions is not an acidic buffer?