A fertilized and brooded egg is coated varnish It never gives rise to a chick why?

Explanation:

- For the development of an embryo inside the egg, oxygen from outside air is essential which diffuses inside through pores present in the eggshell.

- If we coat or block these pores with any material including varnish, gaseous exchange cannot occur that will eventually lead to suffocation or death of the developing embryo thereby ultimately the egg will never hatch into a chick.