Answer:
(OH-)=2,86 x10 ^-9 M.
Step-by-step explanation:
Both pH and pOH have a relationship to belonging to the same aqueous solution: the expression of the Kwater (ionic product of the water Kw) is used:
(H3O+) x (OH-) = 1x10^-14
(3.5 × 10^−6) x (OH-)= 1x10^-14
(OH-)= 1x10^-14/(3.5 × 10^−6)
(OH-)=2,86 x10 ^-9 M