Photodegradation: which statement is true?

• A. Sunlight Can Breakdown Pesticides
• B. Pesticides Degrade Only in Water
• C. Sunlight Has No Effect on Degradation
• D. Pesticides Degrade Solely Due to Soil Moisture

Answer: (A)

Photodegradation is the breakdown of pesticides caused by light energy, especially sunlight. When pesticides absorb photons from the sun, chemical bonds can break directly (direct photolysis) or reactions can be driven by reactive species formed in the presence of light (indirect photolysis). This means sunlight can drive pesticide degradation on surfaces exposed to the sun or in clear water where light can reach the compound.

That’s why the statement that sunlight can break down pesticides is true. The other ideas misrepresent the role of light: degradation is not restricted to water, light has no effect, and soil moisture alone isn’t the sole driver of degradation—moisture and biological processes can influence other pathways, but they don’t replace the need for light in photodegradation.