How do i solve it and what is the answer?

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?

Which sample at stp has the same number of atoms as 18 liters of ne at stp

What is the energy in joules of a mole of photons associated with visible light of wavelength 486 nm?