Which of these does not reflect the periodicity of the elements?

What is the basic difference between the terms electron gain enthalpy and electronegativity?

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.

$(a)$ $Be$ and $Mg$ are alkaline earth metals.
$(b)$ $K^{+}$ has larger radii than $Ca^{2+}$.
$(c)$ All $d$-block elements are transition elements.
$(d)$ $H^{-}$ ion is larger than $F^{-}$.
Incorrect statement is/are

Consider the following elements arranged in a periodic table segment as shown in the image.
Which of the following is/are true about $A^{\prime}, B^{\prime}, C^{\prime}$ and $D^{\prime}$?
$A$. Order of atomic radii: $B^{\prime} < A^{\prime} < D^{\prime} < C^{\prime}$
$B$. Order of metallic character: $B^{\prime} < A^{\prime} < D^{\prime} < C^{\prime}$
$C$. Size of the element: $D^{\prime} < C^{\prime} < B^{\prime} < A^{\prime}$
$D$. Order of ionic radii: $B^{\prime+} < A^{\prime+} < D^{\prime+} < C^{\prime+}$
Choose the correct answer from the options given below:

If the electronic configuration of $A^{-}$ is $[Ar] \ 4s^2 \ 3d^{10} \ 4p^1$,then $A^{+2}$ will belong to which group and period?