Question

Which of the following is(are) the merit(s) of Mendeleev's periodic table?

• A. Could also predict the properties of these unknown elements
• B. Grouping of chemically dissimilar elements.
• C. Position given to isotopes.
• D. Presence of anomalous pairs.

Answer 1

Answer: (A)

Could also predict the properties of these unknown elements

A)Mendeleev could also predict the properties of these unknown elements, on the basis of the properties of the elements lying adjacent to these vacant spaces.

He predicted the presence of three elements. They were named as Eka boron, Eka-aluminium and Eka-silicon. The properties of these three elements were similar to the actual elements discovered later.

Eka-boron was similar to Scandium, Eka-aluminium was similar to Gallium and Eka-silicon was similar to Germanium.

It is the merit of Mendeleev's periodic table and all other options are demerits of it.

B)Some elements placed in the same sub-group varies in the properties.

Ex. Manganese is placed with halogens which totally differ in properties.

C) Isotopes had to be given the same position though isotopes of the same elements have different atomic masses.

D) The element of higher atomic mass ex. Cobalt [58.93u] has been placed before an element of lower atomic mass ex. Nickel [58.71u].

These are anomalous pairs.

Hence, the correct option is $\text{A}$