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

The scientists who explained that the greenhouse effect and the Earth's atmosphere function in a similar way were ...... .

Global warming may result in

What is green chemistry?

Write down the reactions involved during the formation of photochemical smog.

Given below are two statements :
Statement $I$ : If $BOD$ is $4\,ppm$ and dissolved oxygen is $8\,ppm$,then it is a good quality water.
Statement $II$ : If the concentration of zinc and nitrate salts are $5\,ppm$ each,then it can be a good quality water.
In the light of the above statements,choose the most appropriate answer from the options given below :