During an experiment called a flame test, metal ions are heated in the flame of a gas burner. A characteristic color of light is emitted by these ions in the flame when the electrons

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

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c. electrical charges of ionic bonds.