What is the oxidation number of P in PF6−?

According to periodic trend, which of the following most likely has the highest ionization energy? kr be ni sc

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?

How have the greenhouse gasses increased from the year 2000 to 2018