What is the reagent used for testing fluoride ion in water?

Mention the types of atmospheric pollution.

$A$ farmer is using pesticides in his field. He uses the produce from his field as food for fish. He is told that the fish are not fit for human consumption because large amounts of pesticides were found in the fish cells. How is this possible? Explain.

Ozone is a toxic gas and a strong oxidizing agent. However,it is essential in the stratosphere. Explain what would happen if it were to disappear completely from the stratosphere.

Which of the following is responsible for photochemical smog?

$CF_xCly$ [where $x + y = 4$] compounds are not useful because .....