Which statement is true about two isotopes of the same element?

They have the same mass number.
They have different numbers of protons.
They have different locations on the periodic table.
They have different numbers of neutrons.

Question

Which statement is true about two isotopes of the same element?
 
  
 They have the same mass number. 
 They have different numbers of protons. 
 They have different locations on the periodic table. 
 They have different numbers of neutrons.

thomaster · Answer

Isotopes are variants of an element. They have the same number of protons, but a different amount of neutrons.

By the way:
This question would fit better in the chemistry group.