I don't know what I'm supposed to do, can someone explain this to me please???

What is the maximum number of electrons that an atomic orbital can contain?

Write the balanced equation for a reaction between aqueous nitric acid (hno3) and solid lithium metal (this is a single replacement reaction)

11. phosphorus-32 is radioactive and has a half life of 14 days. how much of a 124 mg sample of phosphorus-32 is present after 56 days? a) 7.75 mg b) 15.5 mg c) 31.0 mg d) 62.0 mg