Final answer:
Emphysema would be diagnosed by the formation of bullae in the lungs on a chest x-ray.
Step-by-step explanation:
Emphysema is a chronic lung disease characterized by the breakdown of lung tissue. On a chest x-ray, emphysema would be diagnosed by the formation of bullae. Bullae are large air pockets that form in the lungs due to the destruction of alveolar walls. These bullae appear as round, lucent areas on a chest x-ray.