Suppose a piece of sodium metal gains 2.05 g of mass after being exposed to air. Assume that this gain can be attributed to its reaction with oxygen. (a) What mass of O2 reacted with the Na? (b) What mass of Na reacted? (c) What mass of Na2O formed?

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.

For a patient with the following pes statement and interventions, which would be the most appropriate monitoring and evaluating data? pes statement: inadequate calcium intake related to food and nutrition related knowledge deficit as evidenced by statements that the only dietary source of calcium is milk and she believes that she is lactose intolerant. patient’s nutrition prescription is for a diet providing 1200 mg calcium per day. patient was provided with in-depth nutrition education on alternative dietary and supplement sources of calcium. a. calcium intake (at subsequent visit) b. knowledge assessment by asking patient to identify food sources from menus and shopping list (at the end of the current visit) c. serum calcium (at next visit) d. both a and b e. both a and c

Answer asap need by wednesday morning explain how a buffer works, using an ethanoic acid/sodium ethanoate system including how the system resists changes in ph upon addition of a small amount of base and upon addition of a small amount of acid respectively. include the following calculations in your i. calculate the ph of a solution made by mixing 25cm3 0.1m ch3cooh and 40cm3 0.1m ch3coo-na+. [ka = 1.74 x 10-5 m] ii. calculate the ph following the addition of a 10cm3 portion of 0.08 m naoh to 500cm3 of this buffer solution. iii. calculate the ph following the addition of a 10cm3 portion of 0.08 m hcl to 200cm3 of the original buffer solution.