Astudent is given a sample of a calcium sulfate hydrate. he places the sample in a dry, covered crucible and weighs it. the total mass (crucible, cover, and hydrate) is 18.89918.899 g. the crucible and cover together had previously weighed 17.65517.655 g. he then heats the crucible to redness for 10 minutes with the cover slightly ajar. after the crucible cools, he weighs the crucible and its contents; the mass is now 18.63918.639 g, due to the loss of water of hydration. what is the mass of the original sample? mass of original sample : g what is the mass of the anhydrous (dehydrated) sample? mass of anhydrous sample : g what is the mass of the water that is driven off? mass of water driven off :

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.

2points what is the job of a scientist? a. to answer ethical questions. b. to write laws based on his or her knowledge. c. to ask and answer scientific questions. d. to ignore facts that do not support his or her theory.

Which type of orbits are found in the principal energy level n = 2 a - s b - s, f c - s, d d - s, p e - s, p, d