Which substance is a binary compound?

A. Barium

B. Beryllium

C. Carbon dioxide

D. Calcium Hydroxide

A binary compound is a compound that contain two different chemical elements in it. These compounds may be molecular or may also exist in other forms such as solid. In this case Barium and Beryllium are not binary compounds since they are independent elements, Calcium hydroxide is also not a binary compound since it has more than two chemical elements. Therefore, carbon dioxide is the binary compound since it contains two chemical elements (carbon and oxygen)