What defines matter in the context of physics and chemistry?

Matter is fundamentally defined as anything that has mass and occupies space. This means that for something to be classified as matter, it must have physical substance that can be measured in terms of its mass—this encompasses all physical objects, including solids, liquids, and gases.

In physics and chemistry, the concept of matter is crucial because it relates to the behavior of substances and their interactions, features central to both fields. The definition captures not only tangible objects but also particles that may not be visible to the naked eye, such as atoms and molecules, as they have mass and take up space.

While some other options mention aspects that might relate tangentially to matter, they do not comprehensively encompass the definition. For example, emitting light is not a prerequisite for being considered matter, and weight alone does not encapsulate the broader nature of matter—including gases, which may not have weight in the traditional sense when compared to solids. Thus, the correct answer provides the most accurate and complete understanding of matter in the context of physics and chemistry.