AIR POLLUTANTS MIXING UP WITH RAIN CAN CAUSE ______ IN FRESHWATER LAKES.Question 13Answera.weak alkalib.low pHc.strong alkalid.high pH

To answer the question about the effect of air pollutants mixing with rain and its impact on freshwater lakes, we need to consider the following:

Understanding the Implications of Air Pollutants

1. Air Pollutants and Acid Rain: When air pollutants, particularly sulfur dioxide (SO₂) and nitrogen oxides (NOₓ), mix with rainwater, they can lead to the formation of acid rain. This rain is more acidic than normal rainwater, which is typically around a neutral pH of 7.

2. Effect on pH Levels: As these pollutants combine with rain, they form sulfuric and nitric acids, consequently lowering the pH of freshwater lakes. A lower pH indicates an increase in acidity.

Evaluating the Choices

• a. weak alkali: This would imply a basic solution, which is unlikely in the case of acid rain.
• b. low pH: Correct, as acid rain would result in a decrease in pH, indicating an increase in acidity.
• c. strong alkali: Similar to option a, this implies a basic solution which doesn't fit the scenario.
• d. high pH: Indicates alkalinity and is inconsistent with the effects of acid rain.

Conclusion

Given the explanation above, the correct answer is:

b. low pH

This option correctly reflects the impact of air pollutants in rain leading to more acidic conditions in freshwater lakes.