Nitric acid
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H
O
O
O
N
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Oxygen has 4 electrons in covalent bonds.
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Assign 2 of these 4 electrons to O.
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Oxygen has 2 unshared pairs.
Assign all 4 of
these electrons to O.
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Therefore, the total number of electrons
assigned to O is 2 + 4 = 6.
Formal charge of O