What can you do to pure, solid iron to chemically change it?

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 statement best describes the flow of energy in this scenario

What mass of natural gas (ch4) must you burn to emit 276 kj of heat?