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)

Select all of the statements which are true. electrons are located in shells or orbits around the atom. electrons orbit slowly around the atom. electrons travel in one flat path around the nucleus of an atom. the valence of an atom is determined by the number of electrons in the atom's outermost shell.