U-232
u-235
u-236
u-238
these nuclei all have a different number of
question 2 options:
electrons
neutrons
protons
nucli

Neutrons

Explanation:

All the elements are isotopes of each other. The only difference is in the value of neutrons. Change in electron does not affect the mass number of atom. If there's a change in the proton number, it cease to exists as that same atom rather corresponding to the respective element with that number of proton. The number of proton in an element is usually referred to as the atomic number since it identifies with that particular element.

²³²U, ²³⁵U, ²³⁶U, ²³⁸U all have the same number of proton (atomic number) but different number of neutrons. Combination of proton sand neutrons give atomic mass of an element and which is the number attached to the atomic letter (U).