Question

1)Cr2O3+H2 =>2)Fe+HCI =>3)Ca+HNO3=>

Answer 1

Cr2O3 + 6H2 = 2Cr + 3H2O
Fe + 2HCl = FeCl2 + H2
4Ca + 10HNO3  = 4Ca(NO3)2  + NH4NO3  + 3H2 O (если кислота очень разбавленная)

Answer 2

1. The balanced chemical equation for the reaction between Cr2O3 and H2 is:

Cr2O3 + 3H2 → 2Cr + 3H2O

2. The balanced chemical equation for the reaction between Fe and HCl is:

Fe + 2HCl → FeCl2 + H2

3. The balanced chemical equation for the reaction between Ca and HNO3 is:

Ca + 2HNO3 → Ca(NO3)2 + H2

Note that in each of these balanced chemical equations, the number of atoms of each element is equal on both sides of the equation. This is necessary to ensure that the law of conservation of mass is followed, which states that the total mass of the reactants must be equal to the total mass of the products in a chemical reaction.