Find the $pH$ of a buffer solution prepared by mixing $300 \, mL$ of $0.3 \, M \, NH_3$ and $500 \, mL$ of $0.5 \, M \, NH_4Cl$. Given $K_b$ for $NH_3 = 1.8 \times 10^{-5}$.

Calculate the $pH$ of a buffer solution containing $0.027 \ M$ weak acid and $0.054 \ M$ of its salt with a strong base,if the $pK_{a}$ is $4.2$.

Which of the following solutions will act as a buffer solution?

$1 \times 10^{-3} \ \text{mole}$ of $HCl$ is added to a buffer solution made up of $0.01 \ \text{M}$ acetic acid and $0.01 \ \text{M}$ sodium acetate. The final $pH$ of the buffer will be (given, $pK_{a}$ of acetic acid is $4.75$ at $25^{\circ} \text{C}$)

$A$ buffer solution with $pH = 9$ is prepared by mixing $NH_4Cl$ and $NH_4OH$. Calculate the number of moles of $NH_4Cl$ dissolved in $1.0 \, L$ of $1.0 \, M \, NH_4OH$ solution. (Given: $K_b(NH_4OH) = 1.8 \times 10^{-5}$)

Which of the following will form a basic buffer solution?