In thermodynamics, what is an extensive property?

An extensive property is indeed defined as a property that depends on the amount of substance present in the system. This means that as the size or mass of the system increases, the value of the extensive property also increases. Examples of extensive properties include volume, mass, and total energy. When you double the amount of a substance, you typically double the extensive properties.

The other choices describe different concepts in thermodynamics. One option refers to intensive properties, which are independent of the system size, like temperature or density. Another option discusses properties that show constancy concerning pressure changes, which is not characteristic of extensive properties. Lastly, there is the mention of properties measurable at absolute zero, which pertains to specific thermodynamic principles but does not correlate to the definition of extensive properties. Thus, the definition aligns correctly with the description of option B.