There are 18. In each molecule of Fe(NO3)2 there are 6 oxygen atoms because you have 2 nitrate (NO3) components which each contain 3 oxygen atoms. 2 x 3 = 6. Because you have 3 molecules of Fe(NO3)2, you need to multiply 6 by 3, which gives you 18 oxygen atoms.
Forming a covalent bond
A covalent bond is formed when two atoms share a pair of electrons. Covalent bonding occurs in most non-metal elements, and in compounds formed between non-metals.
These shared electrons are found in the outer shells of the atoms. Usually each atom contributes one electron to the shared pair of electrons.
The slideshow shows how a covalent bond forms between a hydrogen atom and a chlorine atom, making hydrogen chloride.
Structures of a hydrogen atom and a chlorine atom.
1. A hydrogen atom with one electron and a chlorine atom with 17 electrons
Molecules
Most covalently bonded substances consist of small molecules. A molecule is a group of two or more atoms joined together by covalent bonds. Molecules of the same element or compound always contain the same number of atoms of each element.
The atoms in a molecule are always joined together by a covalent bond. Substances that are made up of ions do not form molecules.
Sizes of atoms and simple molecules
A small molecule contains only a few atoms, so atoms and small molecules have a similar range of sizes. They are very small, typically around 0.1 nm or 1 × 10-10 m across.
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Answer: The equation is written below.
Explanation:

According to Stoichiometry of the reaction:
2 moles of phosphate ions reacts with 1 mole of aluminum sulfate to produce 2 moles of aluminum phosphate precipitate and 3 moles of sulfate ions.
Aluminum phosphate is an odorless and white crystalline solid
The chemical equation is written above.
water plus oxygen equals rust so keep water away from the iron to prevent rusting or dry the iron off then apply alchohol to cleanse it
Boiling liquids that want to escape gas