Let's analyze the chemical equation step-by-step to identify the number of oxygen atoms in the reactants and the products.
#### Chemical Equation:
[tex]\[ H_2CO_3 \rightarrow H_2O + CO_2 \][/tex]
### Step 1: Count Oxygen Atoms in the Reactant
The reactant is \( H_2CO_3 \).
1. H_2CO_3:
- This molecule contains 3 oxygen atoms.
Therefore, the number of oxygen atoms in the reactant is \(\boxed{3}\).
### Step 2: Count Oxygen Atoms in the Product
The products are \( H_2O \) and \( CO_2 \).
1. H_2O:
- This molecule contains 1 oxygen atom.
2. CO_2:
- This molecule contains 2 oxygen atoms.
Summing the oxygen atoms in both products:
[tex]\[ 1 \text{ (from } H_2O\text{) } + 2 \text{ (from } CO_2\text{) } = 3 \][/tex]
Therefore, the number of oxygen atoms in the products is \(\boxed{3}\).
### Final Answers:
- The number of oxygen atoms in the products is \(\boxed{3}\).
- The number of oxygen atoms in the reactant is [tex]\(\boxed{3}\)[/tex].