Which one of the following elements corrodes rapidly ?

Corrosion is the gradual deterioration of metals when exposed to environmental factors like moisture and air [3]. Among the given options, iron corrodes most rapidly through a process specifically known as rusting [1]. When iron is exposed to moist air for extended periods, it reacts to form a reddish-brown, flaky coating of hydrated iron oxide (rust) [3]. Unlike aluminum, which forms a thin, tenacious, and self-passivating layer of aluminum oxide that prevents further deep corrosion, iron rust is porous and flaky, allowing moisture and oxygen to penetrate deeper into the metal, leading to continuous and rapid destruction [4]. Silver and zinc also corrode, but at significantly slower rates; silver forms a black tarnish of silver sulphide [5], and zinc is often used as a sacrificial coating to protect iron because its own corrosion rate is relatively controlled [4].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > 1.3.1 Corrosion > p. 13
2. [3] Science-Class VII . NCERT(Revised ed 2025) > Chapter 4: The World of Metals and Non-metals > Activity 4.5: Let us experiment > p. 50
3. [2] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > 3.5 CORROSION > p. 53
4. [4] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > 3.5.1 Prevention of Corrosion > p. 54
5. [5] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 9: Distribution of World Natural Resources > silver > p. 34