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

Simran and Ria were enjoying dancing in the rain. Suddenly, a question struck Ria's mind: "How does rain fall on Earth?" To this, her elder sister Simran explained the water cycle: how clouds are formed when water evaporates due to the heating of water bodies, rises, expands, and cools to form tiny droplets that grow larger to form clouds, which then sprinkle rainwater onto the Earth. Simran also told Ria that this rainwater is essential and precious and must be conserved.
$(a)$ Which values are displayed by Simran?
$(b)$ Why is water conservation necessary?

What are the two ways in which carbon dioxide is fixed in the environment?

What is the importance of the carbon cycle?

What is meant by biogeochemical cycle? Name the two essentials which are transferred between different components of the biosphere.

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