Which of the following is significant for water pollution?

Arrange the following greenhouse gases in the correct decreasing order of their contribution to global warming.

The chemical entities present in the thermosphere of the atmosphere are

Which among the following is not a component of photochemical smog?

Fill in the blanks:
$(1)$ Deficiency of fluoride is responsible for ............. .
$(2)$ The upper limit of lead concentration in drinking water is ............. .
$(3)$ The maximum limit of nitrate in drinking water is ............. .
$(4)$ ............. and ............. chemicals act as poisons for the nervous system.

How does the greenhouse effect contribute to global warming? Explain.