Radon

Definitions

1. A surname from German.
2. The chemical element (symbol Rn, formerly Ro) with atomic number 86. It is an odorless, colorless, chemically inert but radioactive noble gas.
   uncountable
3. Radon-222 (²²²₈₆Rn), the most stable isotope of said element.
   uncountable
4. Johann Radon (1887-1956), an Austrian mathematician with results in measure theory, functional analysis and geometry.

Equivalents

CEFR level