The dissociation constant of $HCN$ is $5 \times 10^{-10}$. The $pH$ of the solution prepared by mixing $1.5 \, mole$ of $HCN$ and $0.15 \, mole$ of $KCN$ in water and making up the total volume to $0.5 \, dm^3$ is (in $.302$)

Find $pH$ of the resultant solution formed by the addition of $500 \ mL$ $0.1 \ M$ $Ba(OH)_2$ and $500 \ mL$ $0.6 \ M$ $NH_4Cl$ in $1 \ L$ pure $H_2O$ at $25 \ ^oC$ (Use $\log \ 2 = 0.3$,$\log \ 3 = 0.5$,$\log \ 5 = 0.7$,$K_b(NH_3) = 10^{-5}$)

$pH$ of a solution of $10 \ mL$ $1 \ N$ sodium acetate and $50 \ mL$ $2 \ N$ acetic acid $(K_a = 1.8 \times 10^{-5})$ is approximately

Derive the Henderson-Hasselbalch equation.

For a $10 \, mL$ solution containing $0.1 \, M \, NH_4Cl$ and $0.01 \, M \, NH_4OH$,which of the following additions will not change the $pH$ of the solution?

Which among the following pairs is not an acidic buffer?