$1.$ When a $27\mathrm{.}7$ mL sample of a $0\mathrm{.}480$ M aqueous hydrocyanic acid solution is titrated with a $0\mathrm{.}455$ M aqueous sodium hydroxide solution, what is the pH after $43\mathrm{.}8$ mL of sodium hydroxide have been added? pH$=$

$2.$ What is the pH at the equivalence point in the titration of a $20\mathrm{.}1$ mL sample of a $0\mathrm{.}338$ M aqueous nitrous acid solution with a $0\mathrm{.}386$M aqueous potassium hydroxide solution? ph$=$

$3.$ A $22\mathrm{.}0$ mL sample of $0\mathrm{.}223$ M ethylamine, C$2$H$5$NHz$,$ is titrated with $0\mathrm{.}216$ M perchloric acid. At the titration midpoint, the pH is $...$

Use the Tables link in the References for any equilibrium constants that are required.

Answer the three questions i asked pls$!$