🔍 Key Concepts

• Behavior of liquefied flammable gas (LFG) when pressure is released • Difference between physical changes (like phase change) and chemical reactions (like corrosion or caustic attack) • Relative density of LFG vapor vs. air

💭 Think About

• Ask yourself: when a liquefied gas under pressure is suddenly released, what is the first thing it tends to do—change phase, react chemically, or move in a particular direction? • Which options describe a chemical effect on materials, and which describe a basic physical process that would happen to almost any liquefied gas released to the atmosphere? • Think about whether LFG is typically heavier or lighter than air—does it normally ‘rise,’ or tend to stay low and spread out?

✅ Before You Answer

• Identify which choices describe corrosive or caustic chemical attack rather than a general behavior of LFG. • Determine which option describes a phase change from liquid to gas. • Recall that many LFG vapors are heavier than air, so be careful with any answer that assumes they naturally move upward.