What is the main source of chlorofluorocarbon $(CFC)$ pollution?

Which of the following components is present in the troposphere?

Fill in the blanks:
$(1)$ Carbon dioxide is found in the ................. layer.
$(2)$ $A$ high concentration of carbon dioxide is responsible for ................. .
$(3)$ ................. gas is used in air conditioners.
$(4)$ Acid rain causes damage to the ................. monument (wonder).

Identify the coldest region among the following layers of atmosphere.

The acceptable level of carbon monoxide gas $(CO)$ in the atmosphere in $ppm$ level is

Statues and monuments in India are affected by acid rain. How?