<prompt> In case of pneumothorax -Cavity in lungAir fills in pleural spacePus fills in pleural spaceBlood in pleural space  <response>: Ans. is b i.e., Air fills in pleural space Pneumothorax- Air in pleural cavity Empyema- Pus in pleural cavity Hemothorax- Blood in pleural space Hydrothorax- Fluid in pleural cavity 