Question

Name unknown elements at the time of Mendeleef

Answer 1

the unknown element at the time of mendeleef are ekasilica and ekaboron

Answer 2

Mendeleev's periodic table could predict the properties of several elements on the basis of their positions in periodic table.

The name of undiscovered elements are :

Eka Boron

Eka Aluminum

Eka Silicon

Eka in sanskrit " means  first " that means first comes the element Boron and then the undiscovered element.

Later they were discovered as

Eka Boron --- scandium

Eka Aluminum---- gallium

Eka Silicon- germanium