Answer:
synthesis
Step-by-step explanation:
The reaction equation properly written is shown below:
4Al + 3O₂ → 2Al₂O₃
A synthesis reaction is a form of combination of atoms. It involves the formation of a single product from two or more reactants.
Decomposition is the formation of two or more products from a single reactant.
Single replacement is a reaction in which one substance is replacing another.
In double displacement, there is an actual exchange of partners to form new compounds.