Question

there are some vacant places in the mendeleevs periodic table. in some of this places the atomic masses are seen to be predicted. enlist three of these predicted atomic masses along with their group and period .

Answer 1

1) he said gallium would take place below aluminim
its properties will be same as the aluimium
he called it eka-aluminium --- EL2O3 (similar to AL2O3)
68amu (atomic mass)
 
2) eka silicon (germanium) 72amu (atomic mass)

3)eka -boron (scandium) 44amu (atomic mass)