question: Certain air pollutants form which liquid when dissolved in water droplets in the air?
distractor3: citrus
distractor1: water
distractor2: base
correct_answer: acid
support: Acidity is an important factor for living things. For example, many plants grow best in soil that has a pH between 6 and 7. Fish may also need a pH between 6 and 7. Certain air pollutants form acids when dissolved in water droplets in the air. This results in acid fog and acid rain, which may have a pH of 4 or even lower. The pH chart in the Figure above and the Figure below reveal some of the adverse effects of acid fog and rain. Acid rain not only kills trees. It also lowers the pH of surface waters such as ponds and lakes. As a result, the water may become too acidic for fish and other water organisms to survive.