Which property affects how a pesticide binds to soil?

Which property affects how a pesticide binds to soil?

• A. Electrical charge
• B. Mass number
• C. Solubility
• D. Molar mass

Answer: (A)

Electrical charge governs how a pesticide sticks to soil because soil particles such as clays and organic matter carry electric charges on their surfaces. The pesticide’s charge determines whether it is attracted to or repelled by those surfaces. Positively charged pesticides bind strongly to the negatively charged sites on clay minerals and organic matter through ion exchange. Negatively charged pesticides can still bind via other interactions (like bridging with cations) but the binding behavior is largely controlled by charge. Neutral pesticides depend more on hydrophobic interactions with organic matter than on electrostatic attraction. Mass number or molar mass don’t set how pesticides bind to soil, and while solubility affects movement with water, the fundamental driver of sorption to soil surfaces is the pesticide’s electrical charge.

Electrical charge governs how a pesticide sticks to soil because soil particles such as clays and organic matter carry electric charges on their surfaces. The pesticide’s charge determines whether it is attracted to or repelled by those surfaces. Positively charged pesticides bind strongly to the negatively charged sites on clay minerals and organic matter through ion exchange. Negatively charged pesticides can still bind via other interactions (like bridging with cations) but the binding behavior is largely controlled by charge. Neutral pesticides depend more on hydrophobic interactions with organic matter than on electrostatic attraction. Mass number or molar mass don’t set how pesticides bind to soil, and while solubility affects movement with water, the fundamental driver of sorption to soil surfaces is the pesticide’s electrical charge.