<prompt> True about normal expirationAt the end of normal expiration air in lung is ERVChest wall has a tendency to move outward which is balanced by inward recoil of alveoliIn expiration pleural pressure is equal to alveolar pressureMuscles that elevate the chest cage are classified as muscles of expiration  <response>: Your expiratory reserve volume is the amount of extra air -- above anormal breath -- exhaled during a forceful breath out. The average ERV volume is about 1100 mL in males and 800 mL in females Ref: guyton and hall textbook of medical physiology 12 edition page number:324,325,326 