Q. The atoms of the elements having same difference between mass number and atomic number are called:
Answer: Isotones
Notes: Atomic number is the number of protons present in an atom; while, mass number is the sum of the number of protons and the neutrons of an atom. Isotones are the atoms of different elements which contain same number of neutron with different mass number and atomic number. For example, Silicon and Phosphorous have same number of neutron 16 with different mass number 30,31 and atomic number 14,15.