What defines matter?

Matter is defined as anything that has mass and occupies space. This definition encompasses all forms of matter, regardless of their state—solid, liquid, gas, or plasma. Mass is a measure of the amount of substance in an object, while taking up space refers to the volume that matter occupies.

This understanding is fundamental in chemistry and physics, as it highlights that all physical substances, living or non-living, are made up of matter. The concept does not limit matter to just the visible or tangible items; instead, it includes entities that may not be directly observable, such as gases or microscopic particles.

In contrast, the other options are more restrictive or inaccurate. While visibility and tangibility can describe many forms of matter, they exclude a vast range of substances that are not directly observable, such as gases like oxygen or carbon dioxide. Specifying only solid-state items or living organisms further narrows the definition and misses many forms of matter, including liquids and many fundamental components that are crucial for understanding the broader concepts in chemistry.