Explain why chemical equations have to be balanced

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 is not a true statement about dwarf planets? a the kuiper belt contains comets, asteroids, and dwarf planets. b ceres is a dwarf planet located in the kuiper belt. c the largest known dwarf planet in the solar system is named eris.

This question is about electrolysis. metal spoons can be coated with silver. this is called electroplating. suggest one reason why spoons are electroplated?