A 2.5 gm impure sample containing weak monoacidic base (Mol. wt. = 45) is dissolved in 100 ml water and titrated with 0.5 M HCI when of `((1)/(5))^(th)` the base was neutralised the pH was found to be 9 and at equivalent point pH of solution is 4.5. Given: All data at `25^(@)C & log 2 = 0.3.` Select correct statement( s).

Options

A. `K_(b)` of base is less than `10^(-6)`
B. Concentration of salt (C) at equivalent point is 0.25 M
C. Volume of HCl is used at equivalent point is 100 ml
D. Weight percentage of base in given sample is 80%.

Answer

bc