Respuesta :
Answer:
2
Explanation:
In order to balance an equation the same amount of atoms of each element in the reactants (the substances on the left of the arrow) must appear in the products (the substances on the right of the arrow). In this particular case, we see that there are 4 Cr atoms and 3*2 = 6 Oxygen atoms as reactants, and the molecule formed has 2 Cr atoms and 3 Oxygen atoms, so if we multiplied the number of molecules by 2, then the equation get balanced, that is:
4Cr + 3O2 -> 2 Cr2O3
