How did Thomson help our understanding of the atom? O A. He discovered that electrons circled around the nucleus in orbits. O B. He discovered that the atom contained a positive center and negative electrons. O C. He discovered that an atom's mass was found in the nucleus. O D. He discovered that the atom contained smaller particles called electrons.

4al + 3o2 → 2al2o3 what does the "3" in front of o2 stand for? a) it indicates that there are 5 oxygen atoms after you add the coefficient and the subscript. b) it indicates that that there are are total of 6 oxygen atoms all bonded together as a single molecule. c) it indicates that there are 3 oxygen molecules chemically bonded to each other in the reaction. d) it indicates that there are 3 separate oxygen molecules in the reaction.