Alveolar `pO_(2)` is `"_____________"` than the venous `pO_(2)` while arterial `pO_(2)` is `"_____________"` than the alveolar `pO_(2)`.

Answer

To solve the question regarding the relationship between alveolar pO2, venous pO2, and arterial pO2, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding Alveolar pO2**:
- Alveolar pO2 refers to the partial pressure of oxygen in the alveoli of the lungs. This is where gas exchange occurs between the air in the lungs and the blood in the capillaries.

2. **Understanding Venous pO2**:
- Venous pO2 refers to the partial pressure of oxygen in the blood returning to the heart from the tissues. This blood has already delivered oxygen to the tissues and thus has a lower oxygen content.

3. **Comparing Alveolar pO2 and Venous pO2**:
- Since the alveoli are filled with fresh air that has a higher concentration of oxygen, the pO2 in the alveoli is higher than that in the venous blood. Therefore, we can conclude:
- **Alveolar pO2 is higher than venous pO2**.

4. **Understanding Arterial pO2**:
- Arterial pO2 refers to the partial pressure of oxygen in the blood that has just been oxygenated in the lungs and is being transported away from the heart to the tissues.

5. **Comparing Arterial pO2 and Alveolar pO2**:
- After oxygen diffuses from the alveoli into the blood, the arterial blood has a high pO2. However, the arterial pO2 can be slightly lower than the alveolar pO2 due to some mixing of blood and the fact that not all oxygen from the alveoli is absorbed. Therefore, we can conclude:
- **Arterial pO2 is lower than alveolar pO2**.

### Final Answers:
- Alveolar pO2 is **higher** than the venous pO2.
- Arterial pO2 is **lower** than the alveolar pO2.