The answer : protons and neutrons
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For Iron:

For Oxygen:

These are the two chemical symbols for the two elements found in Iron Oxide.
Answer:
1. 48 mols
2. 0.2 M
5. 1.25 L
Explanation:
Molarity= mols divided by liters
Hope this helps not sure about 3 and 4
Answer:
b. Its concentration is half that of the chloride ion
Explanation:
As the calcium chloride formula is CaCl2
CaCl2 <--> Ca + 2 Cl-