Which of these is an example of a physical change? question options: melting a substance breaking chemical bonds forming chemical bonds nuclear decay

What is the number of atoms in 3.54 mol s

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

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.