Which statement is correct about volatile organic compounds?

Which statement is correct about volatile organic compounds?

• A. They are nonvolatile
• B. They have high vapor pressure and low water solubility
• C. They are always water soluble
• D. They are only solids at room temperature

Answer: (B)

Volatile organic compounds are defined by their tendency to evaporate into the air at room temperature. A high vapor pressure means the compound readily enters the gas phase, which is the hallmark of volatility. Low water solubility means they don’t mix well with water, so they tend to partition into air rather than staying dissolved in water, influencing how people are exposed and how the chemical moves in the environment. That combination—high vapor pressure and low water solubility—best describes VOCs, making the statement correct. The other ideas don’t fit: being nonvolatile would contradict their very name and behavior; being always water soluble isn’t accurate for many VOCs, which are poorly soluble; and VOCs are not limited to solids at room temperature, as many are liquids or gases under ambient conditions.

Volatile organic compounds are defined by their tendency to evaporate into the air at room temperature. A high vapor pressure means the compound readily enters the gas phase, which is the hallmark of volatility. Low water solubility means they don’t mix well with water, so they tend to partition into air rather than staying dissolved in water, influencing how people are exposed and how the chemical moves in the environment. That combination—high vapor pressure and low water solubility—best describes VOCs, making the statement correct. The other ideas don’t fit: being nonvolatile would contradict their very name and behavior; being always water soluble isn’t accurate for many VOCs, which are poorly soluble; and VOCs are not limited to solids at room temperature, as many are liquids or gases under ambient conditions.