Which one of the following metals does not react with oxygen, water or acids?

The reactivity of metals is determined by their position in the reactivity series. Sodium (Na) is highly reactive, reacting violently with cold water and oxygen. Iron (Fe) reacts with oxygen and water to form rust and reacts with steam and acids. Copper (Cu) reacts with oxygen when heated to form copper(II) oxide but does not react with water or dilute hydrochloric acid [2]. In contrast, gold (Au) is located at the bottom of the reactivity series, making it an unreactive or noble metal. Gold does not react with oxygen, water (cold or steam), or dilute acids [2]. Its chemical inertness makes it nearly immune to oxidation and corrosion, which is why it does not rust or tarnish over time. Therefore, among the given options, gold is the only metal that remains unreactive toward all three substances.

Sources

1. [2] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Activity 3.9 > p. 41
2. [1] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Activity 3.10 > p. 43