According to Mendeleev's periodic table, what was the atomic mass of Eka-aluminium which was later replaced by Gallium?

Question

Question

This question was previously asked in

SSC CGL 2022 Tier-I Official Paper (Held On : 02 Dec 2022 Shift 3)

Answer 1

The correct answer is 68.

Key Points

Mendeleev's periodic table
- Mendeleev published the periodic table in 1869 but not all the elements were discovered by that time, so he left some spaces under Aluminium and Silicon.
- He examined the relationship between atomic masses and the physical and chemical properties of elements.
- While preparing the periodic table there were a few instances where he had to place elements with a slightly greater atomic mass before an element with a slightly lower atomic mass as he wanted to place elements with similar chemical properties together.
- Periodic law states that "properties of elements are periodic function of their atomic masses.

Additional Information

By his time only 63 elements were discovered.
Mendeleev boldly predicted the existence of certain elements that had not been discovered at that time.
He named them eka-boron, eka-aluminium, and eka-silicon as they have properties similar to that of Boron, Aluminium and Silicon.
Later on, these names were replaced as follows:
Eka-boron =Scandium
Eka-aluminum = gallium
Eka- silicon = Germanium
Further, it was observed that the predicted atomic weights of eka-boron (scandium), eka-aluminium (gallium), and eka-silicon (germanium) are 44, 68, 72, and those of calculated weights are 43.8, 70, and 72.6 respectively.
Eka is a Sanskrit word meaning one.