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Conceptual Problem: A student wants to manufacture a pocket-sized lighter that produces a shower of sparks when the wheel is spun, and also needs a permanent magnet for a science project that is extremely powerful despite its small size. Which specific lanthanide-containing alloy and which specific lanthanide-containing compound should the student choose, and what are their primary roles in these applications? Step 1: Identify the requirement for the sparking mechanism. To get a shower of sparks upon friction, an alloy containing about 95% lanthanide metals combined with iron, known as Mischmetal, is required. Step 2: Explain the role of Mischmetal. Mischmetal is pyrophoric, meaning when it is scraped or struck, small metallic particles break off and instantly ignite in the air due to rapid oxidation, producing bright sparks. Step 3: Identify the requirement for the extremely powerful small magnet. To build a super-strong, compact permanent magnet, the student needs a neodymium-iron-boron magnet (Nd2Fe14B). Step 4: Explain the role of neodymium. Neodymium is a lanthanide whose atoms possess unpaired f-electrons that align their magnetic fields exceptionally well, creating magnetic fields far stronger than traditional iron magnets.