. Mg(s) + 2 H+(aq) – Mg2+(aq) + H2(g)
An experiment is done to find the volume of H2(g)
that is formed when a certain mass of Mg(s) reacts
with excess hydrochloric acid. The net ionic
equation for this reaction is shown. The experiment
is run with a 0.042-gram sample of pure Mg(s) and a
solution of 2.0 M hydrochloric acid.
Calculate the number of moles of Mg in the 0.0420 g sample.

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.

Which is the layer underground where all empty spaces are filled with a combination of air and water ?

Which of the following methods uses the decay of atomic particles in an object to find its exact age? a. fossil dating b. geologic dating c. radioactive dating d. relative dating