The number of the following pairs of elements which exhibit a diagonal relationship is:
$1. B \text{ and } Si$
$2. Be \text{ and } Al$
$3. Li \text{ and } Mg$
$4. Al \text{ and } S$

State whether the following statements are true or false:
$(i)$ As the atomic number increases in a period,the nuclear charge increases,therefore the ionization enthalpy increases.
$(ii)$ As the metallic character of elements increases,the atomic radius generally increases.
$(iii)$ $Mn$ $(Z = 25)$ is a transition element. Although it is a $3d$-orbital element,its position in the periodic table is in the $4^{th}$ period.

Which of the following orders is correct for the property mentioned in brackets?

In which of the following arrangements,the sequence does not strictly follow the property indicated against it?

The electronic configurations of four elements are:
$I. [Xe] \, 6s^1$
$II. [Xe] \, 4f^{14} \, 5d^1 \, 6s^2$
$III. [Ar] \, 4s^2 \, 4p^5$
$IV. [Ar] \, 3d^7 \, 4s^2$
Select the incorrect statement about these elements.

Which element from the following exhibits a diagonal relationship with $Mg$?