Understanding Ozone Properties and Its Role

Ozone (\(\text{O}_3\)) is a molecule made up of three oxygen atoms. It exists primarily in two regions of the atmosphere: the stratosphere and the troposphere, playing different roles in each layer.

Let's examine the statements provided in the options to determine which ones are true regarding ozone.

Statement 2: Ozone is highly reactive

This statement is true. Ozone is a very strong oxidizing agent and is highly reactive. Its reactivity is due to the unstable nature of the \(\text{O}_3\) molecule, which readily breaks down to form diatomic oxygen (\(\text{O}_2\)) and a highly reactive oxygen atom (\(\text{O}\)). This high reactivity makes it useful for applications like sterilization and water purification, but also makes it harmful to living organisms and materials at high concentrations.

Statement 3: Ozone protects us from the harmful UV radiation of sun

This statement is also true. The ozone layer, located in the stratosphere, absorbs a significant portion of the sun's harmful ultraviolet-B (UV-B) radiation. This absorption is crucial for protecting life on Earth from potential damage, including skin cancer, cataracts, and harm to plants and marine ecosystems. Without this protective layer, UV radiation levels at the surface would be much higher.

Statement 4: Ozone is the major constituent of photochemical smog

This statement is true as well. In the troposphere (the lower atmosphere), ozone is considered a secondary air pollutant and is a key component of photochemical smog. Photochemical smog is formed through complex reactions involving sunlight, nitrogen oxides (\(\text{NO}_x\)), and volatile organic compounds (VOCs). Ozone is produced during these reactions and is a major irritant to the respiratory system, contributing to health problems in urban areas experiencing smog.

Conclusion Based on Statements

Since statements 2, 3, and 4 are all true descriptions of ozone's properties or roles, the option stating that "All of the options" are true is correct.

Revision Table - Key Ozone Facts

Additional Information - Ozone Layers and Impacts

It is important to distinguish between stratospheric ozone and tropospheric ozone. Stratospheric ozone is often called "good" ozone because of its protective role against UV radiation. Tropospheric or ground-level ozone is considered "bad" ozone because it is a pollutant that harms respiratory health, vegetation, and contributes to smog.

The depletion of the stratospheric ozone layer, primarily due to human-produced chemicals like chlorofluorocarbons (CFCs), was a major environmental concern. International efforts, such as the Montreal Protocol, have helped in phasing out these ozone-depleting substances, leading to a gradual recovery of the ozone layer.

Conversely, ground-level ozone is increasing in many urban and industrial areas due to pollution from vehicles and industrial processes. Controlling tropospheric ozone requires reducing emissions of its precursor pollutants, like nitrogen oxides and volatile organic compounds.