Animated Solution for Chemistry - Environmental Chemistry: The incorrect statement(s) among (A) - (D) regarding acid rain is (are) : (A) It can corrode water pipes. (B) It can damage structures made up of stone. (C) It cannot cause respiratory ailments in animals. (D) It is not harmful for trees.

The phenomenon of acid rain is one of the most critical environmental challenges of our time. While normal rain is slightly acidic with a pH of around 5.6 due to dissolved carbon dioxide, acid rain takes this to a destructive level.

When pollutants like sulfur dioxide (${\text{SO}}_2$) and nitrogen oxides (${\text{NO}}_x$) are released into the atmosphere from factories and vehicles, they react with water vapor to form strong acids: sulfuric acid (${\text{H}}_2{\text{SO}}_4$) and nitric acid (${\text{HNO}}_3$). This drops the pH of the rain significantly, leading to widespread environmental and structural damage.

Let's evaluate the first two statements regarding the physical damage caused by acid rain.

Statement (A) claims that acid rain can corrode water pipes. This is absolutely correct. The high concentration of ${\text{H}}^{+}$ ions in acid rain reacts vigorously with the metals used in plumbing, such as iron, lead, and copper. For instance, the reaction with iron can be represented as: This corrosion not only destroys the pipes but also leaches toxic heavy metals into our drinking water supply.

Statement (B) states that acid rain damages structures made of stone. Think of the iconic Taj Mahal. Monuments made of marble and limestone are primarily composed of calcium carbonate (${\text{CaCO}}_3$). When sulfuric acid falls on these structures, a devastating chemical reaction occurs: The resulting calcium sulfate is slightly soluble and washes away, leading to a phenomenon often called "Stone Leprosy." Thus, Statement (B) is also correct.

Animals and Trees

Now, let's look at the biological impacts mentioned in the remaining statements.

Statement (C) claims that acid rain cannot cause respiratory ailments in animals. This is factually incorrect. Acid rain contributes to the formation of fine particulate matter, specifically sulfates and nitrates. When inhaled, these microscopic particles penetrate deep into the lungs, causing severe respiratory issues like asthma and bronchitis in both humans and animals.

Statement (D) asserts that acid rain is not harmful to trees. This is a massive misconception. Acid rain is incredibly destructive to forests. It leaches vital nutrients like calcium (${\text{Ca}}^{2+}$) and magnesium (${\text{Mg}}^{2+}$) from the soil, starving the trees. Furthermore, it releases toxic aluminum (${\text{Al}}^{3+}$) ions from the soil, which severely damage the root systems. It also directly damages the protective waxy coating on leaves, hindering photosynthesis. Therefore, Statement (D) is definitively incorrect.

By carefully analyzing the chemistry and environmental science, we have determined that Statements (C) and (D) are incorrect.

This perfectly matches option (a). It is worth noting that some reference materials or older answer keys might contain a typo suggesting that Statement (D) is correct. However, as students of science, we must trust the fundamental chemistry: acid rain is undeniably harmful to trees.