Answer:
C. Atoms have isotopes of an element have different numbers of protons.
Explanation:
The isotopes are the variation in the number of neutrons (neutral charge), with increases the weight of the atom, so the first one, is related to this one.
You have already gotten the balanced equation. And the ratio of mol number of reactants and production is the ratio of coefficient. So there is 6.4/8*11=8.8 mol oxygen needed. The mass is 8.8*32=281.6 g.
