Question

carbon - 12 and carbon - 13 are isotopes of carbon. which of the following statements is correct?
they both have seven protons in the nucleus.
they both have the same mass number.
they both have seven neutrons in the nucleus.
they both have the same atomic number.

Explanation:

• Atomic number: The atomic number of an element is equal to the number of protons in its nucleus. For carbon, the atomic number is 6. So, both carbon - 12 and carbon - 13 have 6 protons (not 7 as in the first option).
• Mass number: The mass number is the sum of protons and neutrons. Carbon - 12 has a mass number of 12 (\(6\) protons \(+ 6\) neutrons), and carbon - 13 has a mass number of 13 (\(6\) protons \(+ 7\) neutrons). So, they do not have the same mass number (eliminating the second option).
• Neutrons: As calculated above, carbon - 12 has 6 neutrons and carbon - 13 has 7 neutrons (eliminating the third option).
• Isotopes definition: Isotopes of an element have the same atomic number (same number of protons) but different mass numbers (different number of neutrons).

Answer:

They both have the same atomic number.