When is a compound considered binary?

when it has at least one double bond
when it has two of the same elements bonded together
when it has two different elements bonded together
when it has two atoms

Isnt it
when it has two different elements bonded together

correct.

Yes, you are correct. A compound is considered binary when it consists of two different elements bonded together. Binary compounds are formed when elements from different groups or families on the periodic table combine. The combination of two different elements forms a new compound with distinct chemical properties.