Answer:
7.208 g
Explanation:
0.4mol x 
= 7.208 g
You are using molar mass of H20 to find the mass. Moles of 0.4 and 1 mol cancel out leaving you with just grams. You get the values in the numerator from the periodic table and the 2(1.01) is because you have 2 of the H in H20
Answer:
:)
Explanation:
If we subtract the atomic number from the atomic mass: atomic mass - atomic number = number of protons + number of neutrons - number of protons. Thus we get the number of neutrons present in an atom when we subtract the atomic number from the atomic mass.