________________precipitation harms buildings and statues, threatens living organisms, and has a pH less than that of normal rain.

• A. Rain
• B. Snow
• C. Hail
• D. Acid

Answer: (D)

Acid precipitation is precipitation with a pH lower than normal rain. It forms when pollutants like sulfur dioxide and nitrogen oxides from burning fossil fuels react in the atmosphere to create sulfuric and nitric acids, which then fall as rain, snow, or other forms. This acidic content causes chemical weathering of materials like limestone and marble found in buildings and statues, and it can corrode metals. It also harms living organisms by acidifying soils and water bodies, altering nutrient availability and harming aquatic life. Normal rain sits around pH ~5.6 due to dissolved carbon dioxide, so precipitation that's noticeably more acidic is described as acid precipitation. The other forms listed are just different ways rain, snow, or hail can fall and aren’t defined by low pH.