A. When the substance is in its gaseous state.
<u>Explanation:</u>
When a substance is expanding against its constant volume and pressure, its temperature increases except when the substance is in gaseous state and not in liquid or solid state. So the internal energy increase in the system not only increases and maintaining the volume and pressure of the system remains constant in its gaseous phase. In the first law of Thermodynamics, it is used specifically that to especially in the case of gaseous system.
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Matter is predominantly know to exist in three states-
-Solid
-Liquid
-Gas
The three states can be interconverted at appropriate temperature and pressure conditions. Each state exhibits unique properties which are influenced by the intermolecular forces that hold the atoms together in these states.
Ans: Thus, Every time matter changes from a liquid to a gas, the matter also experiences a change in the <u>state (or phase)</u>
Allowing organic matter to decompose
A element mixture (key word: mixture) due to the mixture containing 2 different types of elements it can be said that it’s highly likely that the mixture was not a compound but instead of a mixture due to mixture meaning more than 1 material. Hopes this help!