The correct option for the process primarily responsible for the reduction of sulfur dioxide emissions from industrial sources, thereby helping to mitigate acid rain, is **B. Flue gas desulfurization**. ### Detailed Explanation **1. Understanding Sulfur Dioxide Emissions:** - Sulfur dioxide (SO₂) is a significant pollutant produced primarily from the burning of fossil fuels, such as coal and oil, in power plants and industrial processes. - When SO₂ is released into the atmosphere, it can react with water vapor and other chemicals to form sulfuric acid (H₂SO₄), which contributes to acid rain. Acid rain can harm ecosystems, damage buildings, and affect human health. **2. What is Flue Gas Desulfurization (FGD)?** - Flue gas desulfurization is a technology used to remove sulfur dioxide from the exhaust flue gases of fossil-fuel power plants and other industrial processes. - The most common method of FGD involves the use of a wet scrubber, where flue gases are passed through a solution (often limestone or lime) that reacts with SO₂ to form calcium sulfate (gypsum), which can be removed from the gas stream. **3. Why is FGD Effective?** - FGD systems can achieve a high removal efficiency, often exceeding 90% of the SO₂ in the flue gas. - By significantly reducing the amount of SO₂ released into the atmosphere, FGD plays a crucial role in mitigating acid rain and its associated environmental impacts. ### Analysis of Other Options **A. Carbon capture and storage (CCS):** - While CCS is an important technology aimed at reducing carbon dioxide (CO₂) emissions from industrial sources, it does not specifically target sulfur dioxide emissions. Therefore, it is not primarily responsible for reducing SO₂ emissions. **C. Catalytic cracking:** - Catalytic cracking is a process used in petroleum refining to break down large hydrocarbon molecules into gasoline and other products. This process does not address sulfur dioxide emissions and is unrelated to the mitigation of acid rain. **D. Electrolysis:** - Electrolysis is a chemical process that uses electricity to drive a non-spontaneous reaction, often used in the production of metals or the decomposition of compounds. It does not have a direct application in reducing sulfur dioxide emissions from industrial sources. ### Summary of Key Points - **Flue Gas Desulfurization (FGD)** is the primary method for reducing sulfur dioxide emissions from industrial sources. - FGD systems can remove over 90% of SO₂ from flue gases, significantly mitigating acid rain. - Other options like carbon capture, catalytic cracking, and electrolysis do not specifically target sulfur dioxide emissions. ### Revision Summary - **Flue Gas Desulfurization (FGD)** is crucial for reducing SO₂ emissions. - FGD uses chemical reactions (often with limestone) to remove SO₂ from flue gases. - Other methods like CCS, catalytic cracking, and electrolysis do not address SO₂ emissions. - Understanding the role of FGD helps in grasping the broader context of environmental chemistry and pollution control.