B. carbon-13 is not an allotrope of Carbon.
Allotropes<span> are elements on the periodic table that have more than one crystalline form. </span>Isotopes<span> are atoms of the same element with the same atomic number but have a different mass number.
C-13 is an isotope of carbon, not an allotrope.</span>
<span>This would be the atomic mass. In an atom of carbon-12, there are 6 protons and 6 neutrons at rest (electrons have a negligible mass and are usually not part of the overall mass calculation). All atomic masses are based off the measurements of this specific iteration of carbon.</span>
= 30802.53 im pretty sure if im wrong let me know its the best i can do :/