Pennsylvania Esthetician State Board Practice Exam

What is formed when two different elements chemically unite?

1. Mixture

2. Element

3. Compound

4. Solution

The correct answer is: Compound

When two different elements chemically unite, they form a compound. A compound is a substance that consists of two or more different types of atoms bonded together in a fixed ratio, creating a new chemical identity with its own unique properties that differ from those of the individual elements. This process of uniting different elements is an essential concept in chemistry, as it illustrates how elements can interact and combine to produce more complex substances. Compounds can be simple, like water composed of hydrogen and oxygen, or more complex, involving a variety of different elements. In contrast, a mixture refers to a combination of two or more substances that retain their individual properties and do not chemically bond. An element is a pure substance that cannot be broken down into simpler substances and consists of only one type of atom. A solution is a homogeneous mixture of substances in which one or more solutes are dissolved in a solvent, but it does not involve the chemical combination of elements to form new compounds. Thus, the formation of a compound denotes that a chemical reaction has occurred between the elements, leading to a new substance with distinct characteristics.