Which of these defines "matter" in a scientific context?

The definition of "matter" in a scientific context is anything that has mass and takes up space. This definition is foundational in physics and chemistry, as it describes the physical substances that make up the observable universe. Matter can exist in various states, such as solid, liquid, gas, and plasma, and is composed of atoms and molecules.

Understanding this basic definition is crucial because it differentiates matter from other concepts like energy — something that does not have mass or occupy space. This distinction helps in various scientific disciplines, allowing for clear interpretations of experiments, observations, and hypotheses regarding the physical world.

The other options do not accurately reflect the definition of matter. Energy in motion refers to kinetic energy, which is an entirely different concept. A substance that can be transformed may describe some properties of matter, such as its ability to change states, but it doesn't encompass the complete definition of what matter is. The absence of substance refers to a vacuum or void, which is the opposite of what matter represents.