In Mendeleev ’s Periodic Table, gaps were left for the elements to be discovered later. Which of the following elements found a place in the periodic table later
(a) Germanium
(b) Chlorine
(c) Oxygen
(d) Silicon
Ans (a)
Sol.
Chlorine, oxygen and silicon were already included in Mendeleev's periodic table.
Eka-Silicon -- Germanium
Eka-aluminum -- Gallium
were the elements that are left by Mendeleev in his periodic table.