* Triple bonds occur when two atoms share three pairs of electrons. This creates a very strong bond.
Let's analyze each option:
1. CO (Carbon Monoxide): This is the correct answer. Carbon monoxide has a triple bond between the carbon and oxygen atoms.
2. NH3 (Ammonia): Ammonia has single bonds between the nitrogen and hydrogen atoms.
3. BCl3 (Boron Trichloride): Boron trichloride has single bonds between the boron and chlorine atoms.
4. H2O (Water): Water has single bonds between the oxygen and hydrogen atoms.
5. BI3 (Boron Triiodide): Boron triiodide has single bonds between the boron and iodine atoms.
6. H2Se (Hydrogen Selenide): Hydrogen selenide has single bonds between the selenium and hydrogen atoms.
7. H2S (Hydrogen Sulfide): Hydrogen sulfide has single bonds between the sulfur and hydrogen atoms.
8. HO (Hydroxyl Radical): This is a radical (an unstable molecule with an unpaired electron) and has a single bond between the hydrogen and oxygen atoms.
Therefore, the substance with a triple bond is CO (Carbon Monoxide).
