Which of the statements are incorrect ?

Options

A. pH of a solution of salt of strong acid and weak base is less than 7.
B. pH of a solution of a weak acid and weak base is basic if `K_(b) lt K_(a)`
C. pH of an aqueous solution of `10^(-8)` (M) HCl is 8.
D. Conjugate acid of `NH_(2)^(-)` is `NH_(3)`