Question

all of the statues stand outside, in air. air is a mix of gases, but most prominent are nitrogen (n₂), argon (ar), and oxygen (o₂).

why did the statue of liberty turn green after 30 years, but the charging bull did not? in your answer, you should identify the material that coats the statue of liberty in 2024.

Explanation:

The Statue of Liberty’s outer layer is copper. Copper reacts with oxygen, water vapor, and carbon dioxide in air to form a green copper carbonate patina ($CuCO_3·Cu(OH)_2$) over time. The Charging Bull is made of bronze (a copper-tin alloy), but its patina forms more slowly and is less visible, or it may be treated to resist rapid discoloration. In 2024, the Statue of Liberty is still coated by this stable green copper patina.

Answer:

The Statue of Liberty turned green because its copper surface formed a green patina (copper carbonate hydroxide) via air exposure; the Charging Bull (bronze) has slower/less visible patina formation. The 2024 coating is the green copper patina.