which represent 2 different isotopes of the same element? a. carbon - 12 & $^{12}_{6}c$ b. $^{13}_{6}c$ &…

Brief Explanations:

Isotopes are atoms of the same element with the same atomic number but different mass numbers. Carbon - 13 and (^{12}_{6}C) (which is carbon - 12) are both carbon isotopes. In option A, it's the same isotope written in two ways. Option B has an element (carbon) and a different element (calcium). Option D has the same isotope of sodium written in two ways.

Answer:

C. Carbon - 13 & (^{12}_{6}C)