What is the main property of PCBs?

• A. Water solubility
• B. Low melting point
• C. High volatility
• D. Chemical stability and heat resistance

Answer: (D)

Polybrominated biphenyls (PCBs) are defined by their chemical stability and heat resistance. This means they resist chemical breakdown and remain intact at high temperatures, which is why they were used as dielectric fluids in electrical equipment like transformers and capacitors. Their durable, nonreactive nature makes them persist for long periods in the environment, contributing to ongoing regulatory concerns. Water solubility is not a defining feature—they are largely insoluble in water. They are also not known for high volatility or low melting points; in fact, they have high boiling points and are not easily volatilized. The combination of chemical stability and heat resistance best captures why PCBs were useful and why they pose environmental and health risks.