To determine the number of oxygen atoms in the products of the given chemical reaction [tex]\( Al + O_2 \rightarrow Al_2O_3 \)[/tex], we need to follow a method that ensures the correct application of the law of conservation of mass. This law states that the number of atoms of each element must be the same on both sides of the chemical equation.
1. Identify the reactants and products:
- Reactants: Aluminum (Al) and Oxygen (O_2).
- Product: Aluminum oxide ([tex]\(Al_2O_3\)[/tex]).
2. Count the atoms on both sides of the equation:
- Reactant side:
- Oxygen atoms: [tex]\(O_2\)[/tex] consists of 2 oxygen atoms.
- Product side:
- Aluminum oxide ([tex]\(Al_2O_3\)[/tex]) contains 2 aluminum (Al) atoms and 3 oxygen (O) atoms.
3. Focus on the oxygen atoms:
- On the reactant side, there are 2 oxygen atoms from [tex]\(O_2\)[/tex].
- On the product side, the compound [tex]\(Al_2O_3\)[/tex] has 3 oxygen atoms.
Based on this assessment:
- The number of oxygen atoms in the product [tex]\(Al_2O_3\)[/tex] is clearly 3.
Therefore, according to the law of conservation of mass, the number of oxygen atoms in the products of this reaction is 3.
Thus, the correct answer is:
[tex]\[ \boxed{3} \][/tex]