Which of the following is the major factor in deciding soil structure?

$(i)$ In what form do plants utilize nitrogen?
$(ii)$ Why do they need nitrogen?

Name the three processes in which oxygen is used.

Describe the various steps and processes involved in the nitrogen cycle. Also,explain the cycling of nitrogenous compounds in this cycle.

Name four factors that help in the formation of soil from rocks.

State reasons for the following:
$(i)$ Excess burning of coal causes greenhouse effect.
$(ii)$ Soil is a mixture.
$(iii)$ Temperature ranges from $-190^{\circ} C$ to $110^{\circ} C$ on the surface of the moon.