Answer:
Decomposition of water
Explanation:
The chemical equation 2H₂O -> 2H₂ + O₂ shows two water molecules as reactants, and hydrogen and oxygen as products. This indicates that water is being broken down in this reaction. Another word for this is decomposition.
Formation of water would occur if the arrow was facing the other way (if hydrogen and oxygen were the reactants), however this is not the case, so formation would be incorrect.
Combustion reactions involve a substrate reacting with oxygen, usually producing heat.
Replacement of water is not occurring since the water molecules are being broken down.
