🔍 Key Concepts

• Relationship between chlorine-containing refrigerants and formation of phosgene gas when exposed to flame or very high heat • Basic chemical makeup of each option: which contain carbon, chlorine, and sometimes hydrogen vs. simple gases like CO₂ • Typical safety warnings in older refrigeration manuals about torch work and smoking near certain refrigerants

💭 Think About

• First, think about which of these refrigerants are simple gases (like CO₂ or SO₂) versus organic compounds that contain carbon and halogens (like chlorine). Which type is more likely to decompose into phosgene? • Consider which refrigerants have historically required strict precautions about welding, brazing, or open flames because of the risk of toxic decomposition products. • Ask yourself: which of these refrigerants’ names or designations is associated with chlorinated hydrocarbons used in older refrigeration systems?

✅ Before You Answer

• Identify which options contain chlorine in their formula; phosgene formation is associated with chlorine-containing compounds exposed to high heat. • Confirm from your study materials which refrigerant types are known as halocarbons or chlorofluorocarbons (CFCs/HCFCs). • Before choosing, eliminate any choices that are inorganic gases without carbon–chlorine bonds, since those will not decompose into phosgene.