The Elements: Iron

Iron is the fourth most abundant element in Earth's crust, essential for life and industry. It forms red iron oxide when exposed to oxygen and is crucial in biological processes like oxygen transport in hemoglobin and myoglobin. Mars' red color is due to iron oxide, and meteorites provide natural metallic iron. Industrially, iron is vital, forming steel when combined with carbon, used in construction. All iron on Earth originates from stars.

What percentage of the Earth's crust is made up of iron?

• 15%

• 10%

• 5%

• 2%

Why is blood red in color?

• Due to carbon dioxide

• Due to the presence of oxygen

• Because of iron in hemoglobin

• Because of red blood cells

What gives Mars its distinctive red color?

• Iron oxide

• Copper deposits

• Volcanic ash

• Red soil

What is the main advantage of adding carbon to iron?

• It creates a lighter metal

• It makes iron rust-resistant

• It increases iron's melting point

• It forms steel, which is much harder

Where is all the iron on Earth originally formed?

• In volcanic eruptions

• In the stars

• In the ocean

• In the Earth's core