Why is the stability of a compound considered a chemical property?

Here is the explanation of the given question above. When we say chemical stability, it refers whether the chemical will react with air or water because a substance that is stable will not react. When the compound is unstable, this results in the breakdown and formation of a new substance which results in a chemical change. 

There is one s orbital, and there are three p orbitals, five d orbitals, and seven f orbitals. thus, the answer is b. do not confuse the number of orbitals in a subshell with the number of electrons the subshell can hold. each orbital can hold two electrons, so the capacity of an nf subshell is 14 electrons.