How does the corrosion product of carbon steel typically appear?

The corrosion product of carbon steel typically appears as a reddish-brown oxide, commonly referred to as rust. When carbon steel is exposed to moisture and oxygen, a chemical reaction occurs that leads to the formation of iron oxide. This process is known as oxidation, and it results in the reddish-brown color associated with rust. The color is a visual indicator of the iron content in the corrosion product, and it is a common sight on carbon steel that has not been properly protected or maintained.

Other choices present different types of corrosion products or tarnish associated with other metals, which differ in appearance and composition. Bright yellow might be seen with other materials like brass, dark green tarnish is common with copper alloys due to the formation of copper carbonate, and black soot can be associated with burning carbon-based materials or certain types of corrosion in metallic surfaces but does not specifically pertain to the corrosion of carbon steel.