Final answer:
To model a substance in a different state, one should change the temperature, as it affects the kinetic energy of particles and can lead to a change of state without altering the chemical composition of the substance.The right answer is B)
Step-by-step explanation:
When modeling one substance that's in a different state, the aspect that should change is B. The temperature. This is because the state of a substance (solid, liquid, gas) depends largely on the balance between the kinetic energy of its individual particles and the intermolecular forces present. The kinetic energy, which keeps the molecules apart and moving, is chiefly a function of temperature. When the temperature is increased, the kinetic energy of the particles increases, which can cause a substance to change from a solid to a liquid (melting) or from a liquid to a gas (evaporation/boiling). Conversely, a decrease in temperature can result in a gas condensing into a liquid or a liquid freezing into a solid. Therefore, changing the temperature is the primary method of modeling a substance in a different state.
Both the chemical composition of a substance and the total quantity of matter remain constant during a change of state as these changes are physical rather than chemical changes. The volume and density of a substance can also change during a physical change, notably volume increases substantially during the change from liquid to gas, but altering these is the result of the temperature change, not a direct method for inducing a change of state.