Answer is: the hydroxide ion concentration is 3.03·10⁻¹² M.
Chemical dissociation of nitric acid in water: HNO₃(aq) → H⁺(aq) + NO₃⁻(aq).
c(HNO₃) = [H⁺] = 0.0033 M, because nitric acid is strong acid, nitric acid ionize completely so it percent ionization is 100%.
[H⁺] · [OH⁻] = 10⁻¹⁴ M².
[OH⁻] = 10⁻¹⁴ M² ÷ 0.0033 M.
[OH⁻] = 3.03·10⁻¹² M.
