🔍 Key Concepts

• UN/NA identification numbers on hazardous materials placards • Using the Hazardous Materials Table (49 CFR 172.101) or equivalent UN list to match numbers to proper shipping names • Differences in typical uses/chemical families of phosphine, xylenol, furan, and adiponitrile

💭 Think About

• How are four-digit numbers on hazmat placards normally assigned, and where would you look them up in practice? • Do any of these chemicals stand out as a common bulk liquid or tank-containership cargo vs. something usually carried in much smaller quantities? • Based on the names alone, can you sort these substances into gases, aromatics, nitriles, etc., and then think which class 2199 is likely associated with?

✅ Before You Answer

• Remember that four-digit hazmat numbers (UN/NA) are specific and standardized worldwide—each one maps to a single proper shipping name. • Consider which of these substances is commonly transported as a bulk liquid chemical intermediate in containers on a containership. • Verify, in an actual exam or onboard situation, by checking a current hazardous materials/IMDG/UN number table instead of guessing from the names.