everyday science MCQ #48842

All isotopes of a single element share which fixed identity number on the periodic table?

everyday science MCQ #48842

  1. Question 1

    Q1. All isotopes of a single element share which fixed identity number on the periodic table?

    • A) Atomic number
    • B) Mass number only for the most common isotope
    • C) Neutron-to-proton ratio treated as the element’s ID
    • D) Number of electron shells in every ion ever formed

    Answer: Atomic number

    Explanation: The atomic number equals the number of protons in the nucleus and uniquely identifies each element; isotopes of the same element differ in neutron number (and thus mass number) but share the same atomic number.