Calculate the concentration of weak monobasic acid if its degree of dissociation and dissociation constant are $5.0 \times 10^{-4}$ and $5.0 \times 10^{-9}$ respectively.

Calculate pH of 0.002 M KOH solution.

Calculate ' $\alpha$ ' for 0.1 M acetic acid $\left(\mathrm{K}_{\mathrm{a}}=1.0 \times 10^{-5}\right)$

Calculate $\left[\mathrm{H}_3 \mathrm{O}^{+}\right]$in 0.02 M solution of monobasic acid if dissociation constant is $1.8 \times 10^{-5}$.