Concept:Diatomic elements exist naturally as molecules formed by two identical atoms bonded together.
Explanation:The common diatomic elements are hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine.
Among the options, oxygen is a non-metal and exists as
O2, so it is diatomic.
Sodium and iron are metals that occur as single atoms in their solid state, not as diatomic molecules.
Neon is a noble gas and exists as single atoms, so it is monatomic rather than diatomic.
Therefore, the diatomic element in this list is oxygen.
Answer:B. Oxygen