Manufacturing Skill Standards Council (MSSC) Safety Assessment Practice Test

What are formed when a metal is heated above its boiling point and then condensed in cool air?

1. Dusts

2. Gases

3. Vapors

4. Fumes

The correct answer is: Fumes

When a metal is heated above its boiling point and then condensed in cool air, it forms fumes. Fumes are typically small, solid particles that are generated when a metal vaporizes due to extreme temperatures and then condenses upon cooling. This process creates fine particulates that can be inhaled, posing health hazards to workers. Fumes are distinct from other forms like dusts, gases, and vapors. Dusts consist of larger particles that are often created from the mechanical breakdown of materials rather than vaporization and condensation. Gases refer to substances in a gaseous state that do not necessarily condense into solids upon cooling. Vapors are generally associated with substances that evaporate and form gas but do not solidify into particles when cooled in the same manner that fumes do. Thus, fumes specifically arise from the rapid cooling of metal vapors, leading to the formation of solid particles, making this option the most accurate in the context of the question.