What is the maximum number of moles of H2O that can be produced from the reaction of 5.6 mol H2 and 4.7 mol O2?
H2 + O2

Limiting reactant is H2.

Excess reactant is O2.

Maximum 5.6 mol of H2O can be produced.

Explanation:

                               2H2 + O2 > 2 H2O

from reaction         2 mol   1 mol    

given                    5.6mol   4.7mol

calculated            5.6mol   2.8 mol

We can see that  for 5.6 mol H2 only 2.8 mol O2 needed, but we have 4.7 mol O2 given, so we have excess of O2.

Then limiting reactant is H2.

Excess reactant is O2.

                               2H2 + O2 > 2 H2O

from reaction         2 mol                2 mol

given                      5.6 mol             x mol = 5.6 mol