External respiration is Physical/Physiochemical Process.

Explanation

**Step-by-Step Solution:**

1. **Understanding External Respiration**: External respiration refers to the process of gas exchange that occurs in the lungs, specifically in the alveoli. It involves the intake of oxygen from the external environment and the release of carbon dioxide from the blood.

2. **Location of Gas Exchange**: The exchange of gases takes place in the alveoli, which are tiny air sacs in the lungs. This is where oxygen enters the blood and carbon dioxide is expelled from it.

3. **Nature of the Process**: The process of external respiration is primarily a physical process. This means that it involves the movement of gases (oxygen and carbon dioxide) without any chemical change taking place in the gases themselves.

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