Answer:isotopes of an element has same number of proton but different number of neutron.
Step-by-step explanation:
Isotope: The atoms of element having same atomic number but different mass number are called isotope.
Hydrogen has three isotopes called as
1.protium
2.duetrium
3.tritium
All of the isotopes of hydrogen have same atomic number but different masses 1,2,3 respectively.
Isotopes have same outermost shells there for having same chemical properties.
Isotopes have different nuclie due which they have different physical properties.
Tritium the 3rd isotop having diffrent prton to neutron ration emitts radiation there it in traces.