Keisha spilled nail polish remover; after 5 minutes it disappeared from view and the counter was dry. Where are the particles now?
- The particles still exist and moved into the air as gas. (correct answer)
- The particles shrank smaller and smaller until they were gone.
- The particles were destroyed and no longer exist anywhere.
- The particles became air particles and changed into new matter.
Explanation: This question tests understanding that particles of matter still exist even when matter appears to disappear from view (NGSS 5-PS1-1). Students must apply the concept of conservation of matter at the particle level. When nail polish remover (acetone) evaporates, the liquid particles gain energy and spread far apart into the air as gas—they still exist but are now invisible vapor that you can smell. Choice A is correct because it accurately states that the particles still exist and moved into the air as gas, demonstrating understanding that evaporation conserves particles. Choices B, C, and D represent misconceptions that particles shrink to nothing, can be destroyed, or change into air particles, violating conservation of matter principles. To help students: Have them notice the strong smell after nail polish remover evaporates—the fact they can smell it proves acetone particles are still present in the air even though the liquid disappeared from view.