Answer : Isotopes.
Explanation : The nuclides of I-131 and I-133 are classified as isotopes of iodine.
An isotope is each of two or more forms of the same element that contains equal numbers of protons but differ in numbers of neutrons in their atomic nuclei, which makes them differ in relative atomic mass.
This makes them radioactive too.
Answer: These two nucleotides are termed as isotopes.
Explanation: Isotopes are the species of the same element having same number of protons and electrons but different number of neutrons.
Atomic number remains same but their atomic masses are different.
These two nucleotides are the isotopes of Iodine having atomic number 53.
[tex]^{131}_{53}I[/tex] and [tex]^{133}_{53}I[/tex] are classified as Isotopes of Iodine.
