Which one of the following is not a monatomic element ?
Copper
Helium
Iodine
Barium
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC NDA-2 – 2019
A monatomic element is an element that exists stably as individual atoms rather than in molecules composed of two or more atoms. Helium (He) is a noble gas and exists as single atoms, making it monatomic. Copper (Cu) and Barium (Ba) are metals that exist as lattices of individual atoms in their solid state. Iodine (I) is a halogen that exists as a diatomic molecule ($I_2$) in its standard solid state and gaseous state (when it sublimes). Thus, Iodine is not a monatomic element; it is diatomic.