Can you help me rank the following in increasing number of atoms?

Question

Rank the following in order of increasing number of atoms (without using any detailed calculations.)

3.0 * 10^23 molecules of H2O2

2.0 mol CH4

32 g O2

The person that shows me how to get the answer in the most understandable way will get best answer. If there are 2 or more that say it good, I will pick the first that answered.

Answer 1

1 mol is equal to 6.022 x 10^23 atoms

Thus 3E23 is half a mole of peroxide.

2 moles of methane is 12E23 atoms

There are X grams of an atom in 1 mole of that element where X is equal to the atomic number. For oxygen, the weight is 16g/mol.

Since your molecule is O2, you multiply this by 2 since there are two atoms of O per molecule. Thus 32g of O2 is ~1 mol.

If you had a more complex molecule, you'd just sum the weights of each element. For example H2O is (1g/mol + 16g/mol + 16 g/mol) or 33g/mol