Question

Is carbon a diatomic element?

Answer 1

Carbon is not a diatomic element. Diatomic elements are those where two atoms of the element can join to form a single molecule.
Examples include:
H-H
O=O
F-F

The diatomic elements are:
Bromine Iodine Fluorine Chlorine Oxygen Hydrogen Nitrogen

I like the acronym: Br I F Cl O H N (pronounced brifclone - the H is silent!) to help to remember these elements.