Answer:
Changing the subscripts in a chemical equation changes the identity and number of atoms in the molecules involved, which makes the equation incorrect. In the example given, changing the subscript in the product side of the equation from 1 to 2 results in the formation of hydrogen peroxide (H2O2) instead of water (H2O).
The equation H₂ + O₂ → H₂O₂ represents the reaction between hydrogen gas and oxygen gas to form hydrogen peroxide. However, this reaction is not balanced because the number of oxygen atoms on the product side is not equal to the number of oxygen atoms on the reactant side. In the reactant side, there are two oxygen atoms, while in the product side, there are two hydrogen atoms and two oxygen atoms. Therefore, this equation is incorrect and cannot be balanced by simply changing the subscripts.
To balance the equation correctly, coefficients should be added to the molecules to represent the number of atoms involved. For example, the balanced equation for the reaction between hydrogen gas and oxygen gas to form water would be:
2H₂ + O₂ → 2H₂O
This equation represents the balanced reaction where two molecules of hydrogen gas (H2) react with one molecule of oxygen gas (O2) to form two molecules of water (H2O), with equal numbers of atoms of each element on both sides of the equation.