The balanced chemical reaction will be:
C2H2 + 5/2O2 = 2CO2 + H2O
We are given the amount of C2H2 being burned. This will be our starting point.
64.0 g C2H2 (1 mol C2H2 / 26.02 g C2H2) (1 mol H2O/1mol C2H2) ( 18.02 g H2O/1mol H2O) = 44.32 g H2O.
Thus, the answer is 44.32 g H2O.