Question

Why should we breather only through our nose?

Answer 1

Because the nostrils are smaller than the mouth, air exhaled through the nose creates a back flow of air (and oxygen) into the lungs. And because we exhale more slowly through the nose than we do though the mouth, the lungs have more time to extract oxygen from the air we've already taken in.

Answer 2

Answer:

We should breathe only with nose because the oxygen present in the air has some kind of impurities. Our nose has a filter present inside which filters the pure oxygen and transmit it into our body. If we breathe through our mouth then we will take in all the impurities into our body.

hope it helps