Final answer:
A binary compound consists either of a monatomic metal cation and a monatomic nonmetal anion, or two nonmetal atoms in the case of covalent compounds. Ternary compounds, like Ca(OH)2, containing polyatomic ions are not binary.
Step-by-step explanation:
To identify which compound is not a binary compound, one must understand what a binary compound is. Binary ionic compounds consist of a monatomic metal cation and a monatomic nonmetal anion, such as NaCl or CaCl₂. Similarly, binary covalent compounds are formed by two nonmetal atoms held together by covalent bonds, like NO or SO₂. In contrast, ternary ionic compounds involve three elements and often include polyatomic ions. A non-binary compound example would be Ca(OH)₂ which is ternary because it contains the polyatomic ion OH-.