Question

Two openings of pharynx one leading to trachea and other leading to food pipe lie very close to each other yet food we swallow does not enter in our trachea why

Answer 1

because of a cartilaginous flap known as epiglottis .

Answer 2

The food does not enter into trachea because during swallowing, the aperture leading to trachea  (glottis) gets covered by a cartilaginous flap called epiglottis and the food has no other passage except  going into the oesophagus.