Which of the following is the most significant air pollutant in modern times?

What is meant by environmental pollution?

Which of the following metal pollutants is present in the exhaust fumes of vehicles?

Name the acids present in acid rain and state their sources in rainwater.

Two statements are given below.
Statement-$I$: In dry cleaning,the solvent $Cl_2C=CCl_2$ was earlier used and now it is replaced by liquified $CO_2$.
Statement-$II$: In bleaching of paper,$H_2O_2$ was used earlier and now it is replaced by chlorine gas.
Correct answer is

In the stratosphere,most of the ozone formation is assisted by: