What is matter defined as?

Matter is defined as anything that occupies space and has mass. This definition encompasses all physical substances, including solids, liquids, and gases. The key components of this definition are "occupies space" and "has mass," which are fundamental properties of matter.

To elaborate, the concept of occupying space indicates that matter takes up a certain volume in the physical world, which can be measured. The aspect of having mass implies that matter is composed of particles, which contribute to its weight and resistance to acceleration when a force is applied.

The other options, while related to aspects of matter, do not accurately define it. Kinetic energy relates to the motion of particles, but not all matter is in motion. The ability to be observed by the senses refers to the sensory properties of matter, but not all matter is detectable by human senses. Finally, the capacity to undergo a chemical change indicates a specific behavior of certain substances but does not apply universally to all matter, as some substances can exist without undergoing chemical transformations. Thus, the best definition of matter is that it occupies space and has mass.