Cells do not catabolize carbon dioxide because:

a) its double bonds are too stable to be broken
b) co2 has fewer bonding electrons than other organic compounds
c) the carbon atom is completely reduced
d) most of the available electron energy was released by the time the co2 was formed
e) the molecule has too few atoms

if two electrons have the same n, the same ℓ, and the same ml, then they are in the same orbital. the pauli exclusion principle states that no two identical fermions (a fancy word for electrons and other subatomic particles like electrons) may occupy the same quantum state in an atom simultaneously.

the answer to your question is c.

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