Which of the following sets of elements is written in the order of their increasing metallic character?

Why does atomic size decrease as we move from left to right along a period in the periodic table?

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

What property do all elements in the same column of the Periodic Table as boron have in common?

An element $X$ has a mass number of $35$ and the number of neutrons is $18$. Determine the atomic number and electronic configuration of $X$. Also, identify the group number, period number, and valency of $X$.

$(a)$ 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.