The endoskeletons and exoskeletons of various animals are also formed from:

Write the names of three processes in which oxygen is used and one process by which it returns to the atmosphere.

$(a)$ Use of fertilizers for a long period causes soil pollution. Explain it.
$(b)$ Water pollution leads to soil pollution. Justify this statement.

$(i)$ An increase in temperature of the water bodies would lead to water pollution: Explain.
$(ii)$ Suggest any two methods to prevent water pollution.

Give two examples where oxygen is not playing any role in supporting life.

Why does the moon have extreme temperature variations,ranging from $-190\,^{\circ}C$ to $110\,^{\circ}C$,even though it is at approximately the same distance from the sun as the Earth?