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Railways PYQCBT 1 2016

RRB NTPC · Question 78

_________ is used in yellow lamp street lights.

  1. Neon

  2. Nitrogen

  3. Phosphorous

  4. Sodium

Show answer & explanation

Answer: (D) Sodium

Explanation

The yellow street lamps are sodium-vapour lamps, which glow with sodium's characteristic yellow light (589 nm). They are efficient and penetrate fog well.