Which of the following statements is the best explanation for why the embryos look so similar, considering how different an adult fish and pig are? Fish and pigs both need gills. Fish and pigs are both mammals. Fish and pigs share a common ancestor.

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.

that's it!

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