Rust is an iron oxide and formed by the reaction of iron and oxygen in the presence of moisture. So the answer would be C
I am not all understood but for the school to earn money you can:
make
--a raffle
--lotto
-- yard sale
-- class photo
-- origami for sale or something
-- buffet or food sale (example all Friday ice cream sale, 2 livre ice cream)
Answer:

Explanation:
When calculating an empirical formula from percentages, assume you have a 100g sample. This allows you to convert the percentages directly to grams, because X % of 100g is X grams.
So:
24.42 % = 24.42 g Ca, 17.07% = 17.07g N, 58.5% = 58.5g O
The next step is to divide each mass by their molar mass to convert your grams to moles.
24.42/40.08 = 0.6092 mol
17.07/14.01 = 1.218 mol
58.85/15.99 = 3.680 mol
Then you will divide all of your mol values by the SMALLEST number of moles. This gives you whole numbers that are the mole ratio (subcripts) of the empircal formula.
0.6092 mol/0.6092 mol = 1
1.218 mol/0.6092 mol = 2
3.680 mol/0.6092 mol = 6
So the empirical formula is 
The molecular formula of HgCl (m = 5 472.1 g/mol) is Hg2Cl4.
The molecular formula is an expression that defines the number of atoms of each element in one molecule of a compound. It shows the actual number of each atom in a molecule.
<h3>Molecular formula: What is it?</h3>
A chemical formula is a way to communicate information in chemistry about the proportions of atoms that make up a specific chemical compound or molecule. Chemical element symbols, numbers, and occasionally other symbols like parentheses, dashes, brackets, commas, and plus and minus signs are used to represent the chemical elements.
A molecule's molecular formula reveals which atoms and how many of each kind are included within it. No subscript is used if there is just one atom of a certain kind. A subscript is added to the symbol for an atom if it contains two or more of a certain type of atom.
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Answer:
ITS THE LAST ONE AND THE SECOND ONE
Explanation: