The poisonous gas that is released during the combustion of petrol in a car engine is

Green chemistry refers to reactions which . . . . . .

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 :

What is the greenhouse effect?

For your agricultural field or garden,you have developed a compost-producing pit. Discuss the process in the light of bad odour,flies,and recycling of wastes for a good produce.

$CFCl_3$ is responsible for the decomposition of ozone to oxygen. Which of the following reacts with ozone to form oxygen?