How many grams of MgO are produced when 40.0grams of 02 react with Mg?

Question

2mg+O2--->2mgO

Could you please set the problem up?

I think the answer is 101, but I do not know how to get that answer. Thank you

Answer 1

Here is a worked example that will work all of your stoichiometry problems.
http://www.chemteam.info/SigFigs/SigFigs.html