Question

demirtts of Mendeleev's periodic table

Answer 1

Disadvantages >
. |> It could not define proper position for Hydrogen.
|> It was based on atomic masses of elements.For that an isotope of an element had to be placed differently.

Answer 2

1. Dissimilar elements were placed / grouped together
Example- Li,Na,K---Au,Cu,Ag
- F, Cl---Mn
2. Separated similar elements
Example- platinum and gold
3. Isotopes weren't positioned properly
Example- Cl-35 , Cl-37
4. Anomalous pairs
Example - Co-58.9, Ni-58.6