A water sample has a pH of $9.25 .$ The concentration of hydroxyl ions in the water sample is
(A) $10^{-9.25}$ moles/L
(B) $10^{-4.75} \mathrm{mmoles} / \mathrm{L}$
(C) $0.302 \mathrm{mg} / \mathrm{L}$
(D) $3.020 \mathrm{mg} / \mathrm{L}$
A water sample has a pH of $9.25 .$ The concentration of hydroxyl ions in the water sample is
(A) $10^{-9.25}$ moles/L
(B) $10^{-4.75} \mathrm{mmoles} / \mathrm{L}$
(C) $0.302 \mathrm{mg} / \mathrm{L}$
(D) $3.020 \mathrm{mg} / \mathrm{L}$