Final answer:
The statement is false; a decline in sulfur dioxide would result in an increase, not a decrease, in the pH of precipitation. Sulfur dioxide contributes to the formation of acid rain, thereby lowering the pH when present in higher concentrations.
Step-by-step explanation:
The statement that a decline in sulfur dioxide has led to a lower pH in precipitation in the Mid-Atlantic states is false. In fact, sulfur dioxide is one of the primary anthropogenic causes of acid rain. When sulfur dioxide is released into the atmosphere, primarily from the combustion of fossil fuels such as coal, it combines with water vapor to form sulfuric acid, which then falls as acid rain.
This process leads to a lower pH in precipitation, which means the precipitation becomes more acidic, not less. The lower pH can have damaging effects on aquatic ecosystems and man-made structures, such as marble monuments, due to the corrosive nature of acid rain. In the Mid-Atlantic states, the decline in the production of sulfur dioxide due to improved technology and regulations has actually helped to alleviate some of the acid rain problems.