A classic chemistry class demonstration is the burning of magnesium ribbon with a
Bunsen burner. In this demonstration, two chemical reactions are occurring: the
burning of methane gas and the reaction between oxygen and magnesium. Of the
two reactions, what is the only limiting reactant?

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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~ trueboss72

the answer is 0.42 is that is an option. this question provides no info