Answer:
carbon dioxide
Step-by-step explanation:
The substance that is a binary compound is carbon dioxide. A binary compound is composed of two different elements. In this case, carbon dioxide consists of carbon (C) and oxygen (O) elements. The compound is formed by the combination of one carbon atom and two oxygen atoms.
Barium, beryllium, and calcium hydroxide are not binary compounds. Barium is an element itself, while beryllium and calcium hydroxide are compounds that contain more than two different elements.
To summarize, carbon dioxide is the binary compound in the given options as it consists of two different elements, carbon and oxygen.