Multiple choice

Which of the following is not a natural occurring element?

  1. Radium

  2. Uranium

  3. Neptunium

  4. Sodium

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Neptunium (Np) is a transuranic element with atomic number 93, and it was first synthesized artificially in 1940 by bombarding uranium with neutrons. While trace amounts of neptunium-237 can be found in uranium ores as a decay product, it is predominantly synthetic and not naturally occurring like radium, uranium, or sodium.

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