Ozone layer depletion was not noticed until 1979, while CFC’s have been around since 1920s. Why is this?

CFCs take time to enter the stratosphere and remain there for at least 60 years after their initial release

CFCs take time to enter the troposphere and remain there for decades after their initial release

CFCs have some ‘down time’ from when they enter the stratosphere and when they react forming chlorine atoms; the CFCs then react quickly and become harmless

Other chemicals are amplifying the effects of CFCs, allowing the chlorine to last longer in the atmosphere

Ozone layer depletion was not noticed until 1979, while CFC’s have been around since 1920s because CFCs take time to enter the stratosphere and remain there for at least 60 years after their initial release.

Option: A

Explanation:

Ozone layer is found in stratosphere. Ozone plays a dual role in the environment. When it is in the ground surface zone it is a harmful gas but when its in the atmosphere it is a life saving layer which absorbs UV rays and protect human beings and animals from the harmful affect of poisonous gases.

Though ozone layer started depleting from 1920. But it came into notice from 1979 as CFCs take time to enter the stratosphere and remain there for at least 60 years after their initial release.

the value of the 4 in the hundreds place is 400 while the value of th e 4 in the tens place is 40

400 is way bigger than 40.