In Mendeleev's Periodic Table,gaps were left for elements to be discovered later. Which of the following elements found a place in the periodic table later?

Write true or false for the statement: In Mendeleev's periodic table,elements were arranged in the order of their increasing atomic masses and it was also observed that there occurs a periodic recurrence of elements with similar physical and chemical properties.

Give an account of the process adopted by Mendeleev for the classification of elements. How did he arrive at Periodic Law?

Which group of elements could be placed in Mendeleev's Periodic Table without disturbing the original order? Give reason.

What type of oxide would Eka-aluminium form?

Mendeleev predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium.
$(a)$ Name the elements which have taken the place of these elements.
$(b)$ Mention the group and the period of these elements in the Modern Periodic Table.