Answer : D. pOH = 12
solutions turns litmus papers to red : acidic (pH<7)
pH + pOH = 14
A. pOH = 3, pH = 11, alkaline
B. [OH⁻] = 1 x 10⁻⁷ ⇒ pOH = - log [OH⁻]= 7, pOH = pH = neutral
C. [OH⁻] = 1 x 10⁻⁵ ⇒ pOH = - log [OH⁻]= 5, pH = 9, alkaline
D. pOH = 12, pH = 2, acidic