Answer
In pure water, concentrations of [H$_{3}$O$^{+}$] will be the same as concentrations of [OH$^{-}$] because one of each will be produced any time a hydrogen ion transfers from one water molecule to the next.
Work Step by Step
In pure water, concentrations of [H$_{3}$O$^{+}$] will be the same as concentrations of [OH$^{-}$] because one of each will be produced any time a hydrogen ion transfers from one water molecule to the next.