Answer:
CO is the chemical formula for carbon monoxide.
Co is the chemical symbol for cobalt.
W is the chemical symbol for tungsten.
Be is the chemical symbol for beryllium.
HI is the chemical formula for hydrogen iodide.
Explanation:
Chemical symbols are either written as a single uppercase letter (ex. O) or an uppercase letter and a lowercase letter (ex. Na).
Chemicals can be anything else! For example CO or even somthing like LiIO.
