Acid precipitation (acid rain) in the environment is mainly caused by a combination of which gaseous pollutants released into the atmosphere?

Introduction / Context:
Acid precipitation, commonly called acid rain, is an important environmental issue. It damages forests, lakes, buildings and cultural monuments. Acid rain forms when certain gases in the atmosphere react with water vapour to produce acidic solutions that fall as rain, snow or fog. Understanding which gases are mainly responsible helps connect industrial emissions and vehicle exhausts with environmental impacts.

Given Data / Assumptions:

• The phenomenon is acid precipitation with pH values lower than normal rain.
• Options list various combinations of gases and environmental components.
• We assume typical industrial and urban pollution sources.
• We consider gases that form strong acids when dissolved in atmospheric moisture.

Concept / Approach:
The major contributors to acid rain are sulfur dioxide (SO2) and nitrogen oxides (NO and NO2). These gases react with oxygen and water in the atmosphere to form sulfuric and nitric acids. Carbon dioxide dissolves in water to form weak carbonic acid, which contributes slightly to natural acidity of rain, though SO2 and nitrogen oxides are the dominant anthropogenic causes. Other components such as dust, saline or helium do not play the major acid forming role in this context. Therefore, the best answer is the combination that includes sulfur dioxide, carbon dioxide and nitrogen oxides.

Step-by-Step Solution:
Step 1: Identify sulfur dioxide as a major industrial pollutant released from burning coal and oil containing sulfur.Step 2: Recognise that nitrogen oxides are produced in vehicle exhaust and power stations due to high temperature combustion.Step 3: In the atmosphere, SO2 can be oxidised to SO3 and then react with water to form sulfuric acid, H2SO4.Step 4: Nitrogen oxides can be converted to nitric acid, HNO3, via a series of reactions with oxygen and water.Step 5: Carbon dioxide dissolves in rainwater to form carbonic acid, H2CO3, which contributes to natural mild acidity.Step 6: Together, these acids lower the pH of precipitation and cause acid rain.Step 7: Compare with the options and see that only option d explicitly mentions sulfur dioxide, carbon dioxide and nitrogen oxides.

Verification / Alternative check:
Environmental science sources explain that unpolluted rain has a pH of around 5.6 due largely to carbonic acid from dissolved carbon dioxide. In polluted regions, pH can fall to 4 or lower because of additional strong acids formed from SO2 and NOx. This supports the idea that sulfur dioxide and nitrogen oxides, with some contribution from carbon dioxide, are the key gases involved in acid precipitation.

Why Other Options Are Wrong:
Option a mentions hydrogen, oxygen and saline, which are not the main acid forming pollutants. Option b describes general components like water, soil and air but not specific acid forming gases. Option c confuses respiration and seawater, which do not directly cause abnormal acid rain in the way industrial emissions do. Option e includes methane, ozone and helium, which are important in other aspects of atmospheric chemistry but are not the primary causes of acid precipitation.

Common Pitfalls:
Students sometimes believe that any gas released by human activity must contribute equally to acid rain or that carbon dioxide alone is responsible. While carbon dioxide affects climate, acid precipitation is primarily driven by sulfur and nitrogen oxides. Another pitfall is to overlook nitrogen oxides and focus only on sulfur emissions. A clear mental association between acid rain and SO2 plus NOx helps avoid these mistakes.

Final Answer:
Acid precipitation is mainly caused by a mix of sulfur dioxide, carbon dioxide and nitrogen oxides released into the atmosphere.