Answer: PCl₃O
Explanation:
1) The chemical formula tells the composition of a compound in terms of the ratio of number of atoms of each element that consitutes such compound.
2) You use the chemical symbol for each kind of atom (element) and subscripts to the right of each symbol to tell the number of atoms of each element.
3) For example, O₂ means two atoms of oxygen. Al₂O₃ means two atoms of aluminum and 3 atoms of oxygen.
4) Therefore, PCl₃O means a ratio 1 : 3 : 1 for phosphorus, chlorine, and oxygen.
Hence, PCl₃O is the chemical formula of your compound.
Answer: A
Explanation: Protons and neutrons form the nucleus of the atom, with electrons orbiting it.
30% should be the percentage of oxygen if the total mass of fe2o3 is 160.
To know the density you also need to know the volume of the rock.