What is the boiling point of methyl bromide that contributes to its rapid vaporization?

• A. 0 degrees Fahrenheit
• B. 38.5 degrees Fahrenheit
• C. 100 degrees Fahrenheit
• D. -20 degrees Fahrenheit

Answer: (B)

Volatility is what this question is testing. Boiling point is the temperature at which a liquid’s vapor pressure equals atmospheric pressure. A low boiling point means the liquid becomes gas easily at normal temperatures. Methyl bromide has a very low boiling point, so at typical environmental temperatures it readily exists as a gas and can vaporize quickly. That rapid vaporization is why it’s effective as a fumigant, since the vapors can disperse through the air to reach pests. The other temperatures would not explain such quick conversion to vapor at ordinary conditions, which is why a low boiling point best accounts for the observed rapid vaporization. This property also underpins the safety emphasis around handling methyl bromide, given its strong inhalation hazards.