HELP ! in the chemical formula 4NH3, how many total elements are present. (I just need the number)

Order the following from smallest to largest atom, electron, quark, proton, neutron, molecule, nucleus

Americium-241 undergoes fission to produce three neutrons per fission event. if a neutron-absorbing material is mixed in with this sample so that the rate of neutron production drops down to 1.8 neutrons per fission event, which will be effective at achieving a critical mass? check all that apply. remove a deflective shield surrounding the sample. remove absorbent material mixed in with the sample. compress the sample of americium-241.

Uranium can supply energy for the worlds electricity without admitting harmful greenhouse gases which of these statements best describes an outcome of uranium mining