Question

Eka-aluminium and eka-silicon are known as _____________ .

Answer 1

Hint: Eka-aluminum and eka-silicon were predictions of elements made by Mendeleev. These elements lie below aluminum and silicon respectively. Try to identify the elements below aluminum and silicon in their respective groups to arrive at the answer.

Complete answer:
The periodic table also called the periodic table of elements is a tabular display of elements based on their atomic number. Before atomic number, atomic mass was considered the basis for arranging elements.
Mendeleev was the first to arrange elements in the tabular form in increasing order of atomic mass. However, he left spaces in his periodic table as he predicted that another element is going to be placed there which will be discovered later.
In this manner, he left a gap below aluminium and germanium. As he did not know the elements, he named them as eka- aluminium and eka- silicon. He even predicted the approximate masses of the two elements.
Later when other elements were discovered, eka- aluminium was the element gallium which is placed below aluminium in the modern periodic table. Similarly, germanium took the place of eka-silicon which is below silicon in the modern periodic table.

Therefore, the correct answer is option (B).

Note:
The periodic table presented by Mendeleev had some drawbacks as well like,
- Unable to locate hydrogen in the periodic table,
- Increase in atomic mass was not regular while moving from one element to another,
- The isotopes of one element could not be placed or represented in the periodic table.