🔍 Key Concepts

• Galvanic corrosion and how a "sacrificial" metal protects steel or iron • The galvanic series in seawater (which metals are more active vs more noble) • Typical hull and tank protection systems used on steel ships and barges

💭 Think About

• Ask yourself: should a sacrificial anode metal be more active (less noble) or more noble than steel in the galvanic series? • Look at the choices and decide: which metals here are usually valued for being corrosion‑resistant vs for being willing to corrode first to protect steel? • Think about what you actually see bolted to the hulls and rudders of steel vessels, or on outdrives and shafts, specifically labeled as sacrificial anodes.

✅ Before You Answer

• Verify which of the listed metals is commonly sold and installed specifically as sacrificial anodes on steel hulls, rudders, and propeller shafts. • Eliminate metals that are typically used for strength, conductivity, or corrosion resistance, rather than for being consumed to protect other metals. • Confirm that the correct choice is a metal that is less noble than steel in seawater, so it will corrode instead of the steel.