Number of moles = mass of product / molecular mass
=mass of product (MgO) / 40.3
Since the mass of MgO is not given in the question, the correct answer choice cannot be given. However, proceeding witht eh above formula will enable you to find the correct number of moles given the mass of MgO.
1.66 is the answer because it’s is
13 because an atom has the same number of protons as neutrons
Hydrogen is the limiting reactant because when doing a stoichiometry equation for the reactants, hydrogen will be used completely by having a smaller yield and oxygen will be excess (7 moles to be exact)