Western Governors University (WGU) SCIE1020 C165 Integrated Physical Sciences Practice Exam

A chemical compound is defined as a substance that is formed when two or more different elements are chemically bonded together in a specific and fixed ratio. This fixed ratio is crucial because it determines the compound's properties and composition. For example, water (H₂O) is a compound made from hydrogen and oxygen in a 2:1 ratio. The specific arrangement and bonding of the elements in this fixed ratio lead to unique characteristics that differ from those of the individual elements.

In contrast, the other choices describe different concepts. A combination of unlike elements in a varied ratio refers to mixtures rather than compounds, as mixtures do not have a fixed composition. A pure material with physical mixtures implies the presence of components that can be physically separated, which does not apply to chemical compounds that must be broken down through chemical reactions. Lastly, a mixture of substances that can be separated easily describes a heterogeneous or homogeneous mixture, not a compound, because the latter involves a definitive chemical bond between constituents that cannot be simply separated by physical means.