The video explains that over 90% of Earth's ozone is in the stratosphere, forming a protective layer that absorbs harmful UVB rays. In the 1980s, scientists discovered significant ozone depletion over Antarctica and the Arctic, linked to chlorofluorocarbons (CFCs). These stable industrial chemicals release chlorine when exposed to UV light, which then breaks down ozone. The Montreal Protocol was established to phase out CFCs, aiming for ozone recovery by 2050.

What percentage of the Sun's ultraviolet-B rays does the ozone layer absorb?

• 100%

• 50% to 60%

• 70% to 80%

• 93% to 99%

Where was the extreme depletion of atmospheric ozone first recorded in the 1980s?

• Above the Arctic

• Above Antarctica

• Over the equator

• In the Northern Hemisphere

What family of industrial chemicals was found to be damaging the ozone layer?

• Hydrocarbons

• Chlorofluorocarbons

• Nitrogen oxides

• Sulfur compounds

What forms during the sunless winter months above the Earth's poles that aids in ozone depletion?

• Polar stratospheric clouds

• Auroras

• Icebergs

• Snowstorms

What is the name of the international agreement aimed at phasing out CFCs?

• Geneva Convention

• Montreal Protocol

• Kyoto Protocol

• Paris Agreement