When the sentence best describes mass movement

What are the concentrations of hydroxide and hydronium ions in a solution with a ph of 10.2?

You have 125g of a certain seasoning and are told that it contains 76.0 g of salt what is the percentage of salt by mass in this seasoning

In the millikan oil drop experiment they determined that every drop had a charge which was a while number multiple of -1.60x10^-19. if a drop has a total charge of -9.60x10^-19 then how many excess electrons are contained within the drop?