Answer:
2h+02=h20
Explanation:
2 in front of h on left side
2 in front of h on right side
1. __1___ Fe + __1___ S → __1___ FeS. 2. __1___ H2 + __1___ Cl2 → __2___ HCl. 3. __2___ Mg + __1___ O2 → __2___ MgO. 4. __1___ O2 + __2___ H2
