Complete and balance the chemical equation:
`CH_4 + O_2 to CO_2 + "______" + ` heat

Explanation

To complete and balance the chemical equation for the combustion of methane (CH₄), we follow these steps:

### Step 1: Write the unbalanced equation
The unbalanced equation is:
\[ \text{CH}_4 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O} + \text{heat} \]

### Step 2: Identify the products
In a complete combustion reaction of a hydrocarbon like methane, the products are carbon dioxide (CO₂) and water (H₂O). Therefore, we will include water in our products.
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