Final answer:
CI - 36 and CI - 37 are isotopes of chlorine, having different numbers of neutrons but the same number of protons.
Step-by-step explanation:
The isotopes of chlorine, specifically CI - 36 and CI - 37, refer to chlorine atoms that have varying numbers of neutrons in their nuclei but the same number of protons. Each chlorine isotope has 17 protons, which is designated by its atomic number. The mass numbers 36 and 37 represent the sum of protons and neutrons, indicating that chlorine-36 has one neutron less than chlorine-37. Chlorine naturally occurs as 75% chlorine-35 and 25% chlorine-37. Isotopes are important in many scientific and medical applications, including radioactive isotopes like cobalt-60 and iodine-131, which are used in nuclear medicine.