tolong jawab pertanyaan ini yahh.... besok dikumpulin nihhh

n NH4OH = 20 x 0,2 = 4 mmol
n (NH4)2SO4 = 100 x 0,2 = 20 mmol
OH- = Kb nbasa/nasamkonjugasi
= 10^-5 4/2 x 20
= 10^-5 4/40
= 10^-6 M
pOH = 6
pH = 14-6 = 8