Element X has two isotopes. If 72.0% of the element has an isotopic mass of 84.9 atomic mass units, and 28.0% of the
element has an isotopic mass of 87.0 atomic mass units, the
average atomic mass of element X is numerically equal to
o (72.0 - 84.9) (28.0 + 87.0)
o (72.0 x 84.9) + (28.0 x 87.0)
o (72.0 + 84.9) (28.0 + 87.0)
o (72.0 x 84.9) (28.0 x 87.0)
+
100
100

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.

How many moles of air are there in a human lung with a volume of 2.4 l at stp? explain your answer

What is i fracture in the crust called when land move up, down or sideways