Final answer:
Pneumothorax is a condition where the lung collapses due to air leaking into the space between the lungs and the chest wall. It is caused by a break in the pleural cavity wall.
Step-by-step explanation:
Pneumothorax is a condition where air leaks into the space between the lungs and the chest wall, causing the lung to collapse. It is often caused by a break in the pleural cavity wall, such as a puncture or injury. The collapse of the lung can lead to difficulty breathing and other symptoms.