Answer:
Option A. Add a coefficient 2 before Fe and a 3 before H2O
Step-by-step explanation:
Fe₂O₃ + 3H₂ —> Fe + H₂O
The above equation can be balance by as follow:
Fe₂O₃ + 3H₂ —> Fe + H₂O
There are 2 atoms of Fe on the left side and 1 atom on the right side. It can be balance by putting 2 before Fe as shown below:
Fe₂O₃ + 3H₂ —> 2Fe + H₂O
There are 3 atoms of O on the left side and 1 atom on the right side. It can be balance by putting 3 before H₂O as shown below:
Fe₂O₃ + 3H₂ —> 2Fe + 3H₂O
Now the equation is balanced.
Thus, the student should add a coefficient 2 before Fe and a 3 before H2O