When 25 g of diethyl ether (C4H10O) is converted to vapor at its boiling point, about how much heat is absorbed? (heat of vaporization, ΔHvap = 15.7 kJ/mol)

Does anyone know a lot about how to: - calculate mass of magnesium metal - calculate the actual yield of magnesium oxide - calculate the theoretical yield of mgo - calculate the percent yield of mgo - determine the percent yield of mgo - determine the average percent yield of mgo i had to do an online lab and its asking these questions but i have no idea where to start or how to be able to find these things. i can post the chart of the data from the lab or if you can tell me exactly how i can find each.

Which of the following statements concerning the influence of culture on ethnic identity formation is accurate? a. one will reject ethnic identity if cultural stereotypes are encountered. b. if one’s ethnic city is different from the dominant cultural group, then one’s ethnic identity you will become weekend. c. if an the ethnic group is excepted by dominant culture, then ethnic identity formation can be a difficult process. d. similarity to the dominant culture can determine how easy it is for one to except ethnic differences.

The tilt of the earth's axis of rotation is responsible for the a) ocean's tides. b) size of the moon. c) brightness of stars. d) earth’s seasons.