Final answer:
The statement that compounds have properties unlike those of their elements is true. Compounds consist of elements combined in a fixed ratio and exhibit unique characteristics that differ significantly from those of individual elements.
Step-by-step explanation:
The statement 'Compounds have properties unlike those of their elements' is true. Compounds are made up of two or more elements that are chemically combined in a fixed ratio. These elements, when combined, form a new substance with properties that are often significantly different from the properties of the individual elements. For example, water (H₂O) is a compound that is liquid at room temperature and has the ability to extinguish fires, but it is made of hydrogen, a flammable gas, and oxygen, which supports combustion. This shows how compounds exhibit unique characteristics that their constituent elements do not possess on their own.
Another example is sodium chloride (NaCl), commonly known as table salt, which is a compound formed from the combination of sodium, a soft and reactive metal, and chlorine, a corrosive and poisonous gas. Sodium chloride, however, is a stable, edible, crystalline substance with entirely different physical and chemical properties. This transformation denotes the chemical reaction that occurs, resulting in compounds with unique properties.