The best reason I can think of for why we believe that air is a mixture is that freezing air slowly yields different liquids at different temperatures. Liquid nitrogen has a different boiling point than liquid oxygen. They also freeze at different temperatures.
An inguinal hernia is a protrusion of abdominal-cavity contents through the inguinal canal. Symptoms are present in about 66% of affected people. This may include pain or discomfort especially with coughing, exercise, or bowel movements. Often it gets worse throughout the day and improves when lying down.
An indirect inguinal hernia results from the failure of embryonic closure of the deep inguinal ring after the testicle has passed through it. Like other inguinal hernias, it protrudes through the superficial inguinal ring. It is the most common cause of groin hernia.