question_answer

        Explain with examples (i) Atomic number (ii) Mass number (Hi) Isotopes and (iv) Isobars. Give any two uses of isotopes.     

Answer:

                    (i) Atomic number: The atomic number of an atom is equal to the number of protons in the nucleus of an atom. i.e., Z = Number of protons. (ii) Mass number: The mass number is the total mass of the atom due to the sum of the masses of protons and neutrons present in the nucleus. i.e., A = Number of protons + Number of neutrons. (iii) Isotopes: Isotopes are the atoms of the same elements having same atomic number but different mass number. For example, hydrogen has three isotopes. They are called protium , deuterium and tritium . (iv) Isobars: Isobars are the atoms of different elements having same mass number and different atomic number. Calcium and argon have same mass number of 40 but different atomic numbers. Uses of isotopes: (i) Cobalt-60 is a radioactive isotope of cobalt. It is used in radiotherapy treatments of cancer. (ii) C14 is a radioactive isotope of carbon. It is used in carbon dating for estimating the age of old and dead animals, plants, rocks, minerals, etc.