Why is it dangerous to sleep in a closed room where coal is burning or stand in a garage keeping the engine of a car running?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Scenario**: The question asks why it is dangerous to sleep in a closed room where coal is burning or to stand in a garage with a running car engine.

2. **Identifying the Process**: When coal burns or a car engine runs, a combustion process occurs. In an open environment, combustion typically uses sufficient oxygen to produce carbon dioxide and water.

3. **Closed Environment**: In a closed room or garage, the oxygen supply is limited. This lack of oxygen affects the combustion process.

...