I think the answer that you are looking for is B but im not a 100% sure
Chemical change. Compounds and molecules in the milk are reacting with the air and breaking down and forming new molecules.
The noble gases are relatively unreactive because they have a stable octet of valence electrons.
Thus, they do not tend to undergo reactions in which they will gain or lose valence electrons,
However, <em>only He, Ne, and Ar are inert</em>. Kr and Xe combine with other highly reactive elements to form stable compounds.
Compounds that primarily contain carbon are known as organic compounds.
