Kaplan Nursing Entrance Practice Exam 2025 – The All-in-One Guide to Exam Success!

Compounds are defined as substances that are made up of two or more different elements that are chemically bonded together in a fixed proportion. This means that in a compound, the elements combine in a specific ratio, which results in unique properties that are different from the individual elements. For example, water (H₂O) is a compound composed of hydrogen and oxygen in a specific ratio of 2:1. This characteristic of compounds is crucial because it distinguishes them from elements and mixtures, where the proportions of components can vary.

The other statements do not accurately describe compounds. They may imply misconceptions about their nature. For instance, compounds cannot be separated into their constituent elements through physical means; they require chemical reactions for such breakdown. Additionally, compounds always involve multiple elements, rather than consisting of a single type of element. Lastly, while it may seem that a compound cannot be broken down, this is only true in terms of its stable form; they can indeed be broken down chemically into simpler substances. Therefore, the accurate understanding of compounds clearly aligns with the statement regarding their composition and fixed proportions.