. Write important limitation of Mendeleev's Periodic Table

Best Answer

Limitations are: 

(i) Position of hydrogen

It is still not certain whether to place

hydrogen in group I A or VII A.

(ii) Anomalous pairs of elements

Ar (40) and K (39); Co (58.9) and Ni

(58.6); Te (127.6) and I (126.9) the

arrangement was not justified. In this

case, the periodic law is violated.

(iii) Position of isotopes three isotopes

of hydrogen with atomic mass 1, 2,

and 3. According to Mendeleev’s

periodic table these should be placed

at three separate places.