In which of the following options the order of arrangement does not agree with the variation of property indicated against it?

Anything that influences the valence electrons will affect the chemistry of the element. Which one of the following factors does not affect the valence shell?
$(a)$ Valence principal quantum number $(n)$
$(b)$ Nuclear charge $(Z)$
$(c)$ Nuclear mass
$(d)$ Number of core electrons.

Identify the correct statements from the following.
$(i)$ In the periodic table,about $78 \%$ of elements are metals.
$(ii)$ In a group,the metallic character decreases from top to bottom and in a period the nonmetallic character decreases from left to right.
$(iii)$ The element $Ho$ belongs to $f-$block.

As we go from left to right in period $2$ of the periodic table,the gram atomic volume of the elements:

Consider the following four elements which are represented according to the long form of the periodic table. Here $W, Y$ and $Z$ are left,up and right elements with respect to the element $X$. $Y$ belongs to the $16^{th}$ group and $2^{nd}$ period. Then,according to the given information,identify the incorrect statement regarding the given elements.

Which one of the following sets of ions represents the collection of isoelectronic species?