Which of the following statements is not correct regarding the trends observed when moving from left to right across the periods of the Periodic Table?

An atom has an electronic configuration of $2, 8, 7$.
$(a)$ What is the atomic number of this element?
$(b)$ To which of the following elements would it be chemically similar? (Atomic numbers are given in parentheses.)
$N(7), F(9), P(15), Ar(18)$

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

Taking the example of an element of atomic number $16$, explain how the electronic configuration of the atom of an element relates to its position in the modern periodic table and how valency of an element is calculated on the basis of its atomic number.

What would be the nature of oxides formed by the elements on the right-hand side of the periodic table?

The elements $Be$,$Mg$,and $Ca$,each having two electrons in their outermost shells,are in periods $2$,$3$,and $4$ respectively of the modern periodic table. Answer the following questions,giving justification in each case:
$(i)$ Write the group to which these elements belong.
$(ii)$ Name the least reactive element.
$(iii)$ Name the element having the largest atomic radius.