Which of these contain a polyatomic ion? Mark all that apply. A sodium nitride -- Na₃N

B sodium chloride -- NaCl

C sodium bicarbonate -- NaHCO₃

D sodium sulfate -- Na₂SO₄

E sodium hydroxide -- NaOH

F sodium oxide -- Na₂O

Which statement is true about ionic compounds?

Which is the layer underground where all empty spaces are filled with a combination of air and water ?

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.