The reactants in a chemical reaction contain 900 J of chemical energy. The products of the reaction contain 9000 J of chemical energy. Which statement best describes this chemical reaction?

The earth's moon is unusually large. two popular theories of the moon's origin include the "sister world" hypothesis, which states that the moon formed from the same materials as the earth, near enough to the earth that they fell into orbit around each other. a second theory is the "capture" hypothesis, in which the moon formed elsewhere in the solar system, and the earth's gravity pulled it into its orbit. studies of what the moon is made of indicate that some of its materials had to come from the earth or from the same area of the solar system where the earth had formed. at the same time, the moon does not contain much of the material that makes up the earth's core, so the moon could not have formed from the same materials as the earth. how do the two facts above affect the described theories of the moon's origin? a. they show that scientists will never agree on where the moon came from. b. they show that more experiments on moon formation need to be done. c. they show that no theory accounts for the existence of the moon. d. they show that neither theory is complete and entirely correct.

The diagram shows the structures of horse and cat forelimbs. what does the diagram suggest about the evolutionary relationship between these two mammals? a. they have homologous structures, indicating a common ancestor. b. they have analogous structures, indicating a common ancestor. c. they have homologous structures, indicating that they do not have a common ancestor. d. they have analogous structures, indicating that they do not have a common ancestor.

Given sno2 + 2h2 - sn + 2h20 tin oxide reacts with hydrogen to produce tin and water. how many moles of sno2 are needed to produce 500.0 grams of sn?