The correct option is **B. Contact process**. ### Detailed Explanation **1. Understanding Sulfur Dioxide Production:** Sulfur dioxide (SO₂) is a significant pollutant that contributes to acid rain. Acid rain occurs when sulfur dioxide and nitrogen oxides react with water vapor in the atmosphere, forming sulfuric acid (H₂SO₄) and nitric acid (HNO₃). The primary industrial process responsible for the production of sulfur dioxide is the Contact process. **2. The Contact Process:** The Contact process is an industrial method used to produce sulfuric acid (H₂SO₄) from sulfur dioxide. The overall reaction can be summarized as follows: \[ \text{S} + \text{O}_2 \rightarrow \text{SO}_2 \] This sulfur dioxide is then oxidized to sulfur trioxide (SO₃) in the presence of a catalyst (usually vanadium(V) oxide, V₂O₅): \[ 2 \text{SO}_2 + \text{O}_2 \xrightarrow{\text{V}_2\text{O}_5} 2 \text{SO}_3 \] Finally, sulfur trioxide is absorbed in water to produce sulfuric acid: \[ \text{SO}_3 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{SO}_4 \] During this process, sulfur dioxide is released as a byproduct, contributing to atmospheric pollution and acid rain. **3. Why Other Options Are Incorrect:** - **A. Haber-Bosch process:** - The Haber-Bosch process is used to synthesize ammonia (NH₃) from nitrogen (N₂) and hydrogen (H₂) gases. The reaction is as follows: \[ \text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3 \] While this process is crucial for fertilizer production, it does not produce sulfur dioxide and is not related to acid rain. - **C. Fischer-Tropsch synthesis:** - The Fischer-Tropsch synthesis is a method for producing liquid hydrocarbons from carbon monoxide (CO) and hydrogen (H₂). The general reaction can be represented as: \[ n \text{CO} + (2n + 1) \text{H}_2 \rightarrow \text{C}_n\text{H}_{2n+2} + n \text{H}_2\text{O} \] This process is primarily used in the production of synthetic fuels and does not involve sulfur dioxide production. - **D. Chloralkali process:** - The Chloralkali process is used to produce chlorine (Cl₂), hydrogen (H₂), and sodium hydroxide (NaOH) from the electrolysis of brine (saltwater). The reactions involved are: \[ 2 \text{NaCl} + 2 \text{H}_2\text{O} \rightarrow \text{Cl}_2 + \text{H}_2 + 2 \text{NaOH} \] This process does not produce sulfur dioxide and is unrelated to acid rain. ### Summary of Key Points: - The **Contact process** is the primary industrial method for producing sulfur dioxide, which contributes to acid rain. - Other processes like the **Haber-Bosch**, **Fischer-Tropsch**, and **Chloralkali** do not produce sulfur dioxide. - Understanding the reactions and products of these industrial processes is crucial for recognizing their environmental impacts. ### Revision Summary: - **Correct Answer:** B. Contact process is responsible for sulfur dioxide production. - **SO₂ contributes to acid rain** through reactions with water vapor. - **Other processes** (Haber-Bosch, Fischer-Tropsch, Chloralkali) do not produce SO₂. - **Key reactions** in the Contact process involve the oxidation of sulfur dioxide to sulfur trioxide and its conversion to sulfuric acid.