Answer:
y = 35.06 %.
Explanation:
The reaction of fermentation is:
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ (1)
From the reaction (1) we have that 1 mol of C₆H₁₂O₆ produces 2 moles of C₂H₅OH, then the number of moles of C₂H₅OH is:
Now, we need to find the mass of C₂H₅OH:
Finally, the percent yield of C₂H₅OH is:

Therefore, the percent yield of C₂H₅OH is 35.06 %.
I hope it helps you!