Acetylene reacts with hydrogen in the presence of a catalyst to form ethane according to the following reaction:
[tex]C_2H_2(g) + 2 H_2(g) + 8n \rightarrow C_2H_6(g)[/tex]
The pressure of a mixture of acetylene and an excess of hydrogen decreases from 0.100 to 0.042 atm in a vessel of a given volume after the catalyst is introduced, and the temperature is restored to its initial value after the reaction reaches completion. What was the mole fraction of acetylene in the original mixture?