Final answer:
When one mole of C2H2 is used in the reaction, two moles of carbon dioxide are produced due to the stoichiometric relationship depicted in the chemical equation.
Step-by-step explanation:
If one mole of C2H2 was used in the chemical reaction 2C2H2 + 5O2 → 4CO2 + 2H2O, then according to the stoichiometric coefficients, the correct statement would be "two moles of carbon dioxide were produced from this reaction." This is because the stoichiometric coefficients indicate the ratio of moles that react or are produced. For every 2 moles of C2H2, 4 moles of CO2 are produced. Therefore, if we start with 1 mole of C2H2, we would end up with half the amount of CO2, which is 2 moles.