Question

Write any two major short comings of mendeleevs periodic table how have these been removed in the modern periodic table

Answer 1

Mendeleev's periodic table was based on atomic mass of elements ...so placing isotopes was a problem which had same atomic numbers but different atomic masses
in the modern periodic table this problem was solved as it is based on atomic numbers


cobalt and nickel have the same atomic mass so they were placed under the same box.
however they have different atomic numbers so in the modern periodic table they got individual places