Compound formed when hydrogen reacts with oxygen.

Answer

To determine the compounds formed when hydrogen reacts with oxygen, we can follow these steps:

### Step 1: Identify the Reactants
The reactants in this reaction are hydrogen (H₂) and oxygen (O₂).

### Step 2: Write the Chemical Reactions
1. **Formation of Water (H₂O)**:
- When hydrogen reacts with oxygen, one of the primary products is water. The balanced chemical equation for this reaction is:
\[ 2H_2 + O_2 \rightarrow 2H_2O \]
This indicates that two molecules of hydrogen react with one molecule of oxygen to produce two molecules of water.

2. **Formation of Hydrogen Peroxide (H₂O₂)**:
- Another compound that can be formed when hydrogen reacts with oxygen is hydrogen peroxide. The balanced chemical equation for this reaction is:
\[ 2H_2 + O_2 \rightarrow H_2O_2 \]
In this case, two molecules of hydrogen react with one molecule of oxygen to produce one molecule of hydrogen peroxide.

### Step 3: Conclusion
The two compounds formed when hydrogen reacts with oxygen are:
- Water (H₂O)
- Hydrogen Peroxide (H₂O₂)