Chemical or molecular formulas? Symbols from the periodic table are used to show which atoms are present in a molecule and subscripts show the number of atoms and of each type in the molecule.
You need the unit of g however you must convert to moles before you can use the mole ratio to find the moles of iron, you used the molar mass of iron to find the grams of iron. since F e 2 o 3
Explanation:
The given data is as follows.
Mass of a lead atom = 
Volume = 2.00 
Density = 11.3 
As it is mentioned that 1 cubic centimeter contains 11.3 grams of lead.
So, in 2 cubic centimeter there will be 
of lead atoms.
One lead atom has a mass of . Therefore, number of atoms present in 22.6 g of lead will be as follows.
= 
Thus, we can conclude that there are of lead are present.
This may help you.
1. Calculate molecular mass of CuSO4•5H2O
2. Calculate molecular mass of ALL oxygen atoms in CuSO4•5H2O (which are 4 oxygen atoms in CuSO4 and 5 oxygen atoms in H2O so in total its 9 oxygen atoms, thus find molecular mass if 9 oxygen atoms)
3. Do mathematical cross multiplication
Molecular mass of CuSO4•5H2O - <span>1.67×<span>10<span>−2</span></span>moles</span>
molecular mass of 9 oxygen atoms - X moles
so
X= <span>1.67×<span>10<span>−2</span></span>moles</span><span> * molecular mass of 9 oxygen atoms / Molecular mass of CuSO4•5H2
and get the answer :3</span>
