Molarity can be defined as the number of moles of solute in 1 L solution.
Molarity of Na₂SO₄ solution - 0.200 M
this means there are 0.200 moles in 1 L solution
Molar mass of Na₂SO₄ - 142 g/mol
therefore mass of Na₂SO₄ in 1.00 L - 0.200 mol x 142 g/mol = 28.4 g
a mass of 28.4 g of Na₂SO₄ is present in 1.00 L
You can make 10 because that is the most N2 you have. The first one that runs out limits further molecules to be made
We add up all the various atoms:
C: 55
H: 72
Mg: 1
N: 4
O: 5
55 + 72 + 1 + 4 + 5
= 137
The answer is B.
