What is the pH of 0.02 M NaOH solution?

Dissociation constant of propionic acid is $$1.32 \times 10^{-5}$$. Calculate the degree of dissociation of acid in $$0.05 \mathrm{~M}$$ solution.

Solubility of $$\mathrm{AgCl}$$ is $$7.2 \times 10^{-7} \mathrm{~mol} ~\mathrm{dm}^{-3}$$. What is it's solubility product?

A substance containing hydrogen and releasing H$$^+$$ in aqueous medium is acid. Identify theory suggesting this concept, from following.