Mebdeleev's classification was a great improvement over contemporary tabulation of the elements by Newlands and Lothar Meyer because
(i) it grouped the elements together more accurately in vertical columns.
(ii) it left gaps for elements which were yet to be discovered in nature.
(iii) it made possible the predication of the properties of elements that had not yet been discovered.
(iv) it predicted that atomic masses of certain elements were incorrectely determined.

Options

A. `(i),(ii),(iii),(iv)`
B. `(ii),(iii),(iv)`
C. `(ii),(iii)`
D. `(ii),(iv)`

Answer

A

Explanation

Mendeleev arranged the elements in groups on the basis of similarities in the formulas of compounds formed by these elements. To ensure that the essential to leave spaces. He assumed that these spaces corresponded to unknown elements. He argued that the properties of the missing elements could be predicted on the basis of the chemistry of its neighbors in the same group. For example, the missing element between silicon and tin, called `eka`-silican `(Es)` by Mendeleev. should have properties intermediate between those of silicon and tin.