Question

achievements of mendeleev periodic table

Answer 1

1) it was the first table in systematic order.
2) gaps were left for some unknown elements.
3)he also predicted the properties of some elements like eka boron eka aluminum. etc
4)he left some column for noble gases.

Answer 2

1.the existence of some elements that had not been discovered at that time
2.Mendeleevs periodic table could predict the properties of several element on the basis of their positions in the periodic table .
3.Mendeelev periodic table could accommodate noble gases when they were discovered .