RAS question
The Gupta-era Iron Pillar at Delhi demonstrates that ancient Indians had mastered:
Correct answer: (D) Rust-resistant iron metallurgy.
The Gupta-era Iron Pillar at Delhi demonstrates ancient Indian mastery of rust-resistant iron metallurgy.
Explanation
The Delhi Iron Pillar is evidence of advanced iron metallurgy rather than of craftsmanship in general. Britannica describes it as a Gupta-period iron pillar weighing about 6 tons and standing about 7.2 metres high; it has remained relatively free of rust for more than 1,600 years. Its iron contains about 0.25% phosphorus. This is linked to the formation of a protective passive film of iron hydrogen phosphate, also called misawite. Britannica notes that phosphate reactions form a thin, rust-protective coating of iron hydrogen phosphate hydrate on the surface. Balasubramaniam links this protection to the Indian craftspeople's deliberate selection of metal. The pillar therefore demonstrates corrosion-resistant iron technology based on careful material selection and skilled ironworking, not glass making, gold smelting or paper production.
Why the other options are wrong
- (A) Glass making is not indicated by an iron pillar; the evidence is the pillar's iron composition and its resistance to corrosion.
- (B) Gold smelting is unrelated because the pillar is made largely of iron, and its significance lies in phosphorus-rich iron metallurgy and a rust-resistant surface.
- (C) Paper production has no connection with the pillar's material, construction or rust-resistant surface chemistry.
Concept
This question tests technological achievement in ancient Indian history, especially metallurgy in the cultural and scientific context of the Gupta period. The topic recurs in RAS because material evidence such as the Iron Pillar links archaeology, science and polity in one factual example.