Are C-12, C-13, and C-14 all carbon isotopes?

Yes, they are isotopes.

Explanation:

Isotopes are atoms with the same atomic number Z and a different mass number (A). That is, they differ in the number of neutrons (eg carbon 12, has 6 protons, 6 electrons, and 6 neutrons, carbon 13, 7 neutrons, and carbon 14 8 neutrons).

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.