1) Chemical reaction:
2C2H2 + 5O2 ---> 4CO2 + 2H2O
2) Molar ratios
2 mol C2H2 : 5 mol O2 : 4 mol CO2 : 2 mol H2O
3) proportion with 35.0 mol C2H2
2 mol C2H2 / 4 mol CO2 = 35.0 mol C2H2 / x
=> x = 35.0 mol C2H2 * 4 mol CO2 / 2 mol C2H2 = 70.0 mol CO2.
Answer: 70.0 mol CO2