What is matter defined as?

Matter is defined as a substance that has mass and occupies space. This definition is foundational in both physics and chemistry because it encompasses all physical substances found in the universe. Matter can exist in different states (solid, liquid, gas) depending on the arrangement of its particles and the energy they possess.

The key components of this definition are "mass" and "occupies space." Mass refers to the amount of matter in an object, while occupying space indicates that matter has physical presence and volume. Together, these two criteria help differentiate matter from energy or other non-material phenomena.

The other choices focus on narrower aspects of substances or processes. For instance, one describes weight only, which is not a comprehensive definition as it neglects the importance of volume. Another option refers to a chemical reaction, which is a process involving the transformation of substances rather than a definition of what matter is. Lastly, the mention of a compound made of multiple elements pertains to a specific type of matter but doesn't capture the broader definition needed to encompass all forms of matter.