What is the percentage contribution of $CO$ to the total atmospheric concentration due to forest fires?

In which of the following industries is animal protein produced as waste?

How can photochemical smog be controlled?

$A$ water sample is reported to be highly polluted if the $BOD$ (Biological Oxygen Demand) value of the sample becomes:

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

Some gases are responsible for the heating of the atmosphere (greenhouse effect). Identify from the following the gaseous species which does not cause it.