Natural Science CLEP Prep Practice Exam

In what form of matter can atoms move freely?

1. Solid

2. Liquid

3. Plasma

4. Gas

The correct answer is: Gas

Gas is a form of matter in which atoms are free to move around, making it the only state of matter where atoms are not restricted in their movement. This is because the atoms in a gas have higher energy compared to the atoms in solid or liquid states, which allows them to overcome the intermolecular forces holding them together. In solids, the atoms are tightly packed and have limited movement, while in liquids, the atoms can move past each other but are still held together by intermolecular forces. Plasma is similar to gas in terms of free movement of atoms, but it is a highly ionized gas that is only found in extreme conditions, such as in stars or lightning. Therefore, D is the only correct answer as it reflects the state of matter where atoms have the most freedom of movement.