Question

how does egg get oxygen when it is totally closed and how many days it take to come out​

Answer 1

Answer:

As the developing chick grows it uses the oxygen from the air sack and replaces it with carbon dioxide. The tiny pores in the shell allow the carbon dioxide to escape and fresh air to get in. The chicken egg has more than 7,000 pores in its shell to allow this to happen!

It takes 21 days on average for an egg to hatch once incubation begins.

Explanation:

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