Chemical properties can be determined by heat combustion, how they react with other chemicals, Oxidization (lose electrons, losing hydrogen, gaining oxygen), or toxicity.
Good luck with your assignment :)
Answer:
One atom lf helium has a mass of 4 u
Know that 1 u =1.66. 10-24g
Answer: 
Explanation:
Firstly, we have to find the Molecular mass of potassium oxide (
):
atomic mass: 39 u
atomic mass: 16 u
molecular mass: 
This means that in 1 mole of there are 
and we need to find how many moles there are in 
:
1 mole of ----- of
----- of
This is the quantity of moles in 73.9 g of potassium oxide
Now we can calculate the number of atoms in 73.9 g of potassium oxide by the following relation:
Where:
is the number of atoms in 73.9g of potassium oxide
is the Avogadro's number, which is determined by the number of particles (or atoms) in a mole.
Then:
This is the quantity of atoms in 73.9g of potassium oxide
