In the Modern Periodic Table,which are the metals among the first ten elements?

Compare and contrast the arrangement of elements in Mendeleev's Periodic Table and the Modern Periodic Table.

By considering their position in the Periodic Table,which one of the following elements would you expect to have maximum metallic characteristic?
$Ga$,$Ge$,$As$,$Se$,$Be$

Which element has
$(a)$ a total of three shells,with four electrons in its valence shell?
$(b)$ a total of two shells,with three electrons in its valence shell?
$(c)$ twice as many electrons in its second shell as in its first shell?

Besides gallium,which other elements have since been discovered that were left by Mendeleev in his Periodic Table? (any two)

What were the limitations of Dobereiner's classification?