Question
Define isotopes, isobars and isotones.
Solution
Isotopes: Isotopes are atoms of the same element having same atomic number but different mass numbers. e.g. 
Isobars: Isobars are atoms of different elements having different atomic numbers but the same mass number. e.g. 
are isobars of each other.
Isotones: Isotones are atoms of different elements having same number of neutrons. For example 
