A chemist breaks down a compound into 3.4 moles of carbon and 6.8 moles of oxygen. What is the percent composition by mass of each element in the compound?

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.

Joe shines white light into a bowl half full of water at an angle of incident of 27.5°. calculate the angle of refraction in the water given the indices of refraction for air and water are 1.00 and 1.36, respectively.

Jose and eric were given four samples in lab. the results of their analysis are shown in the table. based on the data they collected, which sample is most likely a metal?