Explain the following:
Ventilators are placed high on the walls of the room.

Explanation

### Step-by-Step Solution:

1. **Understanding the Concept of Hot Air**:
- Hot air is less dense than cold air. When air inside a room is heated, it becomes lighter and tends to rise.

2. **Movement of Hot Air**:
- As the hot air rises, it creates a need for cooler air to replace it. This movement is a natural process due to convection currents.

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