Question

what is Eka-aluminium?

Answer 1

Eka is a sanskrit word meaning one.

Mendeleev predicted that some elements were yet to be discovered. So, he left some gaps in his periodic table so that these undiscovered elements could get a place in his periodic table.

Mendeleev named the undiscovered elements using the word Eka as a prefix, with the name of the preceding element in the same group.

Some elements pridicted by Mendeleev were eka-aluminium which we today call galium. Eka means an element with similar properties to that of aluminium and gallium does have properties similar to aluminium.