Literature has been published stating that the optimal pH for lactase activity is 4.8 with lactose. At this pH, what would be the closest value to the charge on the catalytically active amino acids? (Assume the pKa of the COOH group is 4.5)

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.

water at room temperature is flowing through a pipe with pressure taps located 10 ft apart along one section of the pipe, which are connected to a mercury (s=13.6) manometer.