What element has the symbol 'Np'?

The story behind the answer

Np is the symbol for Neptunium, element 93. The other options have different symbols: Nickel is Ni, Nobelium is No, and Nitrogen is N.

Neptunium was the first transuranic element discovered (1940, McMillan and Abelson at Berkeley) by bombarding uranium with neutrons; the product beta-decayed into Np-239. Its name follows a planetary sequence: Uranium (Uranus), Neptunium (Neptune), and Plutonium (Pluto). Memory tip: on the periodic table, think space steps—U → Np → Pu. Neptunium is radioactive and has niche uses, such as in neutron detectors and as