80 points and brainliest to !
what is happening in the following equation? n2o4 (g) -> 2 no2 (g) a. two units of nitrogen dioxide are synthesizing into one unit of dinitrogen tetraoxide. b. six units of dinitrogen tetraoxide are decomposing into two units of nitrogen dioxide. c. one unit of dinitrogen tetraoxide gas is decomposing into two units of nitrogen dioxide gas. d. nothing; the reactant and the product are the same.

So,

The numbers in front of the chemical species in a reaction signify how many moles of that species are involved in the reaction.  The forward arrow indicates that the reaction is proceeding from left to right, and the backward arrow (rare) indicates that the reaction is proceeding from right to left.  

In this reaction, one mole of sodium cation is reacting with one mole of chloride to form one mole of sodium chloride.  When there are no coefficients in front of the species, the number of moles is understood to be 1.

In this reaction, one mole of magnesium cation is reacting with two moles of chloride to form one mole of magnesium chloride.  The "2" in front of the chloride signifies that there are two moles of chloride involved in the reaction.

The arrow is pointing forward, the reaction is proceeding from left to right, and one molecule is turning into two moles (aka decomposing).  Thus, the correct answer is C.

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!

if you need further assistance, let me know: )

~ trueboss72

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)