Final answer:
True, carbon-12 and carbon-13 are isotopes; carbon-12 has 6 neutrons and carbon-13 has 7 neutrons. They differ in neutron count but not in proton count.
Step-by-step explanation:
The statement "Carbon-12 and carbon-13 are isotopes, so they have different numbers of neutrons" is true. Isotopes are forms of the same element that have the same number of protons but different numbers of neutrons. Carbon-12 has 6 protons and 6 neutrons, while carbon-13 has 6 protons and 7 neutrons, indicating one additional neutron compared to carbon-12. This means that although both isotopes have the same atomic number, which is 6, they have different mass numbers, with carbon-12 having a mass number of 12 and carbon-13 a mass number of 13.
The mass number and atomic number of carbon-13 are 13 and 6, respectively, and for carbon-12, these numbers are 12 and 6, respectively. Therefore, option a is the correct description. When referring to the number of neutrons each has, carbon-12 contains 6 neutrons, and carbon-13 contains 7 neutrons, which corresponds to option a for the number of neutrons in each isotope.