Three elements $B, Si$ and $Ge$ are:

Mention any two trends exhibited by elements when we go from left to right across the period of the periodic table.

What is a metalloid? Name any two of them.

Which one of the following depicts the correct representation of atomic radius $(r)$ of an atom?

$(a)$ Electropositive nature of the element$(s)$ increases down the group and decreases across the period.
$(b)$ Electronegativity of the element decreases down the group and increases across the period.
$(c)$ Atomic size increases down the group and decreases across a period (left to right).
$(d)$ Metallic character increases down the group and decreases across a period.
On the basis of the above trends of the Periodic Table,answer the following about the elements with atomic numbers $3$ to $9$:
$(a)$ Name the most electropositive element among them.
$(b)$ Name the most electronegative element.
$(c)$ Name the element with the smallest atomic size.
$(d)$ Name the element which is a metalloid.
$(e)$ Name the element which shows maximum valency.

$D$öbereiner's system of classification into triads was not found to be useful as he could identify only: