The mass of substance which consists the equal number of particles as 12 grams of Carbon-12 is said to be mole.
For example:
The balanced chemical equation for production of water from hydrogen and oxygen is:
That means 2 moles of 
reacts with 1 mole of 
to give 2 moles of 
.
The given formula is 
.
Hence, 4 represents the number of moles in formula that is 4 moles of 
.
The number of atoms of sodium, 
in is:
The number of atoms of sulfur, 
in is:
The number of atoms of oxygen in, 
in is:
did u ever get the answer ? I’m also on k12 stuck on this lol
This is what I got hope it helps
We are given initially with 1.2 x 1024 molecules of water, added further with <span>5.0 moles of water. we are asked to determine the total number of molecules of water after the addition. We just </span> convert the number of moles to number of molecules. 5 moles of water is equal to 3.011x 10^24 molecules. The total number is that we add the initial and the additional, equivalent to 4.211 x10^24 molecules.
