The Chemistry of Ozone in Stratosphere

Stratosphere is the region extended to:

• 11 km above earths surface

• 50 Km above troposphere

• 85 km above troposphere

• 500 km above mesosphere

Stratosphere is important because of the presence of:

• oxygen layer

• nitrogen layer
• helium layer
• ozone layer

In stratosphere, ozone is formed due to:

• Photodissociation of oxygen

• Photodissociation of CO₂

• Photodissociation of CFC's

• Photodissociation of VOC's

Ozone layer plays vital role in blocking:

• ultraviolet (UV) radiation
• radio waves
• visible light
• infrared radiation

Sunlight breaks oxygen molecules into:

• oxygen ions

• ozone

• oxygen atoms

• oxygen free radicals

Oxygen molecules combines with oxygen free radical to produce:

• ozone

• oxygen radical

• molecular hydrogen

• hydrogen peroxide

Ozone is destroyed by solar radiations but thickness of ozone layer is maintained because:

• equilibrium between the ozone production and destruction

• ozone is not destroyed by solar radiations
• the ozone layer recovered from troposphere

• human activities have no impact on the ozone layer

The chemicals that depleted ozone are:

• Carbon dioxide and methane
• Chlorofluorocarbons (CFCs) and halons
• Nitrogen and oxygen
• Sulfur dioxide and nitrogen oxides

One of them is not responsible for ozone depletion:

• chlorofluorocarbons (CFCs)

• hydrochlorofluorocarbons (HCFCs)

• hydrobromoflurocarbons (HBFCs)

• hydroflorocarbons (HFCs)

What are ozone-depleting substances (ODS):

• a group of chemicals that can break down ozone in the troposphere

• a group of chemicals that can break down ozone in the stratosphere

• a group of chemicals that can produces ozone in the stratosphere

• a group of chemicals that can produces ozone in the troposphere