When does mercury vaporize?

Mercury is unique among metals because it is liquid at room temperature, which means it has a relatively low boiling point compared to other metals. Mercury does indeed vaporize at room temperature, producing mercury vapor, which is a concern due to its toxicity. The boiling point of mercury is approximately 356.6 degrees Celsius (673.88 degrees Fahrenheit), so enough mercury will vaporize at temperatures significantly below this boiling point, especially as room temperature provides the necessary conditions for a portion of the liquid to enter vapor form.

The other options describe scenarios that either do not align with mercury’s properties or do not apply to the conditions under which mercury vaporizes. It is important to understand that while mercury can also vaporize when heated or at high pressures, the question pertains specifically to its behavior at room temperature, making the choice that answers this directly the most accurate.