The ionisation constant of the weak acid HF whose concentration is 0.1 M is $3.5 \times 10^{-4}$ The Equilibrium constant value for the reaction $\mathrm{F}^{-}+\mathrm{H}_2 \mathrm{O} \leftrightharpoons \mathrm{HF}+\mathrm{OH}^{-}$is _________ and the pH of aqueous solution of the weak acid is __________ .

Imagine an R - moiety of a pentapeptide molecule having one $-\mathrm{SH},-\mathrm{CONH}_2,-\mathrm{NH}_2$ groups each and two $-$COOH groups in the amino acids forming the pentapeptide. If the pH is maintained at 13.2, what would be the total number of negative charges on the pentapeptide?

What volume of $0.2 \mathrm{M} \mathrm{CH}_3 \mathrm{COOH}$ needs to be added to 100 ml of $0.4 \mathrm{M} \mathrm{CH}_3 \mathrm{COONa}$ solution to prepare a buffer of pH equal to 4.91 ? ( $\mathrm{pK}_{\mathrm{a}}$ of $\mathrm{CH}_3 \mathrm{COOH}$ is 4.76 )

Solubility product of the sparingly soluble salt $\mathrm{AgBrO}_3$ in aqueous medium is $9.3 \times 10^{-10}$ Calculate the mass in gram of $\mathrm{AgBrO}_3$ present in 100 ml of its saturated solution. (Molar mass of $\mathrm{AgBrO}_3$ is $236 \mathrm{~g} / \mathrm{mol}$ )