How many valence electrons are in the highest occupied energy leve of an atom

How many moles of magnesium is 3.01 x10^22 atoms of magnesium?

Which of the following describes a compound? (hint: carbon and oxygen bo a. a piece of pure carbon, containing only carbon atoms b. oxygen gas surrounding a solid piece of carbon c. a substance made of two oxygen atoms for each carbon atom carbon and oxygen atoms mixed without being bonded together

What is the approximate vapor pressure when the gas condenses at 70 degrees celsius