At `25^(@)C`, pH of a `0.01 M` solution of a monobasic acid `[HA]` is 4. The correct statement(s) regarding HA and its given solution is (are)
A. HA is a weak acid
B. The ionization constant `(K_(a))` of acid is approximately `10^(-6)` at `25^(@)C`.
C. Increasing the temperature of solution would cause the `pH` to decrease.
D. Addition of `0.1 M HCl` solution would lower pH by increasing degree of ionization