Question

position of isotopes in mendeleev's and modern periodic table

Answer 1

mendeleev's periodic table :
position of isotopes -
according to mendeleev's periodic law , isotopes of an element must be given separate
places in the periodic table since they have
different atomic masses . But they were not assigned separate places.

modern periodic table :
position of isotopes -
since all isotopes of an element have the same number of protons , their atomic number is also the same , so they can be put in one set