Assertion (A): Atoms of same elements with different mass number are called isotopes,
Reason (R): The difference in mass number is due to number of neutrons,
Answers
Answer : A is false but R is true .
Reasoning : Atoms of same elements with same atomic number are called isotopes . Atoms of different elements with same atomic mass are called isobars . The difference in mass number is due to number of neutrons because number of neutrons + number of protons is equal to the atomic mass .
More to know : Matter is made up of molecules and molecules are made up of atoms . Atoms are made up of protons , electrons and neutrons . Protons were discovered by Ernest Rutherford . Neutrons were discovered by J Chadwick . Electrons were discovered by J J Thomson . There are many atomic models for example Rutherford model , Thomsan model , Bohr's atomic model etc . The atomic number is equal to the number of protons in the atom . And the number of protons are equal to the number of electrons . The sum of number of protons and neutrons gives us the atomic mass of the element .