50 POINTS FOR THIS! Copper (Cu) reacts with sulfur (S) to form copper sulfide. A scientist adds 12.7 grams of Cu to 3.2 grams of S to start the reaction. At the end of the experiment, there are 15.9 grams of copper sulfide. In this reaction, all of the copper and all of the sulfur react. The scientist then tries to add 13.7 grams of Cu to 3.2 grams of S. There are still 15.9 grams of copper sulfide at the end, but some copper is also left over. In 1-2 sentences, explain how to calculate the amount of remaining copper. Use the law of conservation of mass in the explanation.

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.

In the cathode ray tube experiment, j. j. thomson passed an electric current through different gases inside a cathode ray tube in the presence of an electric field. in which two ways did this experiment change scientists’ understanding of the atom?

What effect does a decrease in temperature have on the overall rate of a chemical reaction? a decrease in temperature decreases . the reaction rate will