Problem 47 - A Complete Resource Book in Chemistry for JEE Main

Question

The absorption of ultraviolet radiation by \(\mathrm{O}_{3}\) (a) makes both the function effective (b) makes no function effective (c) maintains an equilibrium between the concentrations of \(\mathrm{O}_{2}\) and \(\mathrm{O}_{3}\) (d) protects the inhabitants of out planet from injurious radiation

Step-by-Step Solution

Answer

The correct answer is (d): protects the inhabitants of our planet from injurious radiation.

Step 1: Understanding the Role of Ozone

Ozone (O_3) in the Earth's stratosphere plays a crucial role in absorbing ultraviolet (UV) radiation from the sun. This absorption is significant because it prevents the harmful UV radiation from reaching the Earth's surface.

Step 2: Impact on Living Organisms

Ultraviolet radiation can be harmful to living organisms, including humans. It can lead to skin cancer, cataracts, and other health issues if not filtered by the atmosphere.

Step 3: Evaluating the Options

We need to evaluate the provided options in the context of ozone's role in absorbing ultraviolet radiation. - Option (a) 'makes both the function effective' is vague and doesn't specify which functions are being made effective. - Option (b) 'makes no function effective' is incorrect, as ozone absorption of UV radiation has a clear protective function. - Option (c) talks about maintaining equilibrium between O_2 and O_3, which is a separate chemical process involving equilibrium but not directly about UV protection. - Option (d) 'protects the inhabitants of our planet from injurious radiation' accurately describes the protective role of ozone by absorbing UV radiation.

Step 4: Correct Answer Selection

Based on the analysis, the correct option is (d), which states that the absorption of ultraviolet radiation by O_3 protects the inhabitants of our planet from injurious radiation. This reflects ozone's crucial role in shielding living organisms from harmful UV radiation.

Key Concepts

Ultraviolet Radiation Absorption

The ozone layer, primarily found in the Earth's stratosphere, serves as a protective shield against the sun's ultraviolet (UV) radiation. This layer absorbs much of the UV radiation, effectively reducing the amount that reaches the Earth's surface.
Picture the ozone as a filter that catches harmful rays before they can cause damage.

• UV radiation is categorized into UVA, UVB, and UVC, based on wavelength. While UVC is mainly absorbed by the ozone, UVB and UVA are only partially absorbed, allowing some to reach the Earth.
• The absorption of UV radiation by ozone is a natural process that helps balance the chemistry of gases in the atmosphere while also providing crucial protection to all life forms.
• This radiation absorption by ozone ensures that living organisms, including humans, are not exposed to the intense and harmful effects of UV radiation.

Understanding ultraviolet radiation absorption is key to appreciating how vital the ozone layer is for sustaining life on our planet.

Ozone Protection Mechanism

The ozone layer's protective mechanism hinges on its ability to absorb and scatter ultraviolet radiation. This ensures that only a safe amount of UV reaches the Earth's surface.
Without this protective barrier, the sun's rays would be too harsh, greatly impacting all forms of life.

• The ozone itself is a molecule comprised of three oxygen atoms. Its formation and breaking down are part of a cycle that maintains a natural balance.
• When UV radiation hits ozone molecules, it breaks down these molecules. This action actually plays a dual role: absorbing the harmful energy and triggering a sequence that reforms the ozone.
• This cyclical process is essential for the continuous functioning of the ozone layer as Earth's UV shield.

The ozone protection mechanism is not just a passive barrier; it is a dynamic process essential for environmental balance and protection from solar radiation.

Stratospheric Chemistry

Stratospheric chemistry relates to the unique set of chemical reactions occurring within this atmospheric layer, where the ozone resides. It is a complex interplay of creation and destruction of ozone molecules, driven by solar radiation.
The stratosphere is home to the majority of Earth's ozone, forming a distinct layer filled with reactions critical for life.

• Ozone is formed when ultraviolet light strikes oxygen molecules (}_2")), causing them to split into individual oxygen atoms. These atoms then bond with other oxygen molecules, creating ozone (}_3")).
• Concurrently, ozone molecules absorb UV radiation, which can again break them into an oxygen molecule and a free oxygen atom, perpetuating a cycle.
• This ongoing cycle is sensitive to pollutants such as chlorofluorocarbons (CFCs), which can disrupt the equilibrium, thinning the ozone layer.

Stratospheric chemistry ensures that ozone remains an effective shield by dynamically responding to sunlight and pollutants.

Health Effects of UV Radiation

Understanding the health effects of UV radiation highlights the significance of the ozone layer and the need for its protection.
High levels of UV radiation can have dire consequences on both human health and ecosystems.

• For humans, excessive UV exposure is linked to skin conditions like sunburns, skin aging, and an increased risk of skin cancers such as melanoma.
• It can also impair vision, leading to cataracts, which is a leading cause of blindness worldwide.
• UV radiation can also weaken the immune system, reducing the body's ability to fight off certain diseases.
• Beyond affecting humans, UV radiation impacts plants, animals, and aquatic ecosystems, altering growth patterns and harming biodiversity.

By absorbing UV radiation, the ozone layer plays a crucial role in minimizing these health risks and maintaining ecological balance.