Answer:
A) 
Explanation:
m = Mass of water = 38.9
M = Molar mass of water = 18 g/mol
= Avogadro's number = 
The reaction of electrolysis would be

Number of moles of 

From the reaction it can be seen that 2 moles of
gives 1 mole of 
So, number of moles of
produced is

Number of molecules

So,
of oxygen is produced.
Answer:
D: to transport materials through the body.
Explanation:
A: to bring oxygen into the lung. is incorrect because it's respiratory system
B: to put carbon dioxide into all the blood vessels carbon dioxide is exhaled out of the body
C: to expel waste products from the body. is excretory system
Explanation:
According to the law of conservation of mass, mass can neither be created nor it can be destroyed. But it can be simply transformed from one form to another.
Therefore, when
is added to NaCl then the compound formed will have same mass as that of reactants.

Total mass of reactants is (169.87 + 58.44) g/mol = 228.31 g/mol
Total mass of products is (143.32 + 84.99) g/mol = 228.31 g/mol
Thus, we can conclude that mass of the new mixture will stay the same.
Answer:
The person writes a coefficient of 2 in front of Fe2O3 but then writes a 4 for the number of iron (Fe) atoms. Explain this difference.
Explanation:
Can you show me the atoms please? I would be able to help.