Answer: CO
The nature of the bond is related to the distance between them and it also depends on how positive or negative they are. When two atoms approach each other the electrons of each other are attracted to the protons of other. So when atom is attracted to another it gets stressed out by the attractive forces and tries to relive the stress by getting closer. The pull is so strong that the energy level rises when they are separate
A bond formed by atoms sharing electrons is called covalent bond. The strength with which an atom holds shared electron is called electronegativity. CO is a covalent compound because they share a lone pair of electrons and two ordinary covalent bonds between the carbon and the oxygen atom
