Answer:
Since moles are just "some number of particles", and since one O2 molecule contains enough oxygen for two H2O molecules, you need 2.5 moles of O2 for 5 moles of H2O.
Answer: physical
Explanation: freezing and melting are physical changes.
The number of protons and neutrons combined in an atom is called the mass number.
Q14: Our sun
Q15: The strong magnetic reaction in our atmosphere
