The species I and IV have the same atomic number, and different mass numbers. Thus I and IV are isotopes. Option D is correct.
Elements have been present in nature in varying isotopes. Isotopes can be defined as the element with the same atomic number and different mass numbers.
In representing the element with its symbol, the number represented at the superscript before the symbol is the mass number. The number that has been represented at the subscript before the number is the atomic number.
In the given elements:
- I: [tex]\rm ^7^7_3_5X[/tex]: Atomic number = 35
Mass number: 77
- II. [tex]\rm ^7^7_3_3X[/tex] : Atomic number = 33
Mass number: 77
- III. [tex]\rm ^8^1_3_7X[/tex] : Atomic number = 37
Mass number: 81
- IV. [tex]\rm ^8^1_3_5X[/tex] : Atomic number = 35
Mass number: 81
The species I and IV have the same atomic number, and different mass numbers. Thus I and IV are isotopes. Option D is correct.
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