Hey there!:
Given the reaction:
2 C2H2 + 5 O2 → 4 CO2 + 2 H2O
5 moles O2 ------------- 4 moles CO2
3.00 moles O2 ---------- ( moles of CO2 ?? )
moles of CO2 = 3.00 * 4 / 5
moles of CO2 = 12 / 5
moles of CO2 = 2.4 moles
So, molar mass CO2 = 44.01 g/mol
Therefore:
1 mole CO2 -------------- 44.01 g
2.4 moles CO2 ---------- ( mass of CO2 )
mass of CO2 = 2.4 * 44.01 / 1
mass of CO2 = 106 g
Answer A
Hope that helps!