Question

What is theoretical yield of Cr2O3 if the amount of Cr is 0.0382mol and the actual yield of Cr2O3 is 0.0186mol?

4Cr + 3O2 → 2Cr2O3

Answer 1

with 0.0382 moles of Cr, you expect to get 0.0191 moles of Cr2O3

You only got 0.0186 moles, which is
0.0186/0.0191 = 97.38%