The given equation, P4O10 + 6H2O → 4H3PO4, represents a hydration reaction rather than a decomposition reaction. In a decomposition reaction, a single compound breaks down or decomposes into simpler substances. In this case, however, we observe the opposite process where P4O10, which is a compound of phosphorus and oxygen, reacts with water (H2O) to produce a new compound, phosphoric acid (H3PO4).

Hydration reactions involve the addition of water molecules to a compound, leading to the formation of a hydrated product. In this specific reaction, each molecule of P4O10 combines with six molecules of water, resulting in the formation of four molecules of phosphoric acid.

Therefore, the equation provided does not represent a decomposition reaction but rather a hydration reaction, where water is added to P4O10 to form H3PO4.