Why ozone hole forms over Antarctica ? How will enhanced ultraviolent radiation affect us ?

Why does ozone hole form over Antarctica?

How ozone hole is developed?

How does carbon monoxide affect us?

A hollow metal sphere is filled with water through a small hole in it. It is hanging by a long thread and is made to oscillate. Water slowly flows out of the hole at the bottom How will the period of oscillation be affected?

Why do we use the term 'form genera' for fossil plants?

Answer briefly: (a) Why are villi present in the intestine and not in the stomach? (b) How does pepsinogen change into its active form? (c) What are the basic layers of the wall of alimentary canal? (d) How does bile help in the digestion of fats?