Dimensional analysis, Plz hell I don’t understand and plz explain

Embryos of different species look very similar, which shows that the organisms share a ancestor.

How many moles of carbon dioxide will form if 2.5 moles of c3h8 is burned

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?