The correct decreasing order for metallic character is:

The elements $X$,$Y$,$Z$,and $T$ have the indicated electronic configurations. Starting with the innermost shell,which is the most metallic element?

Which elements are classified as metalloids? Name them.

An element $X$ belongs to the fourth period and fifteenth group of the periodic table. Which of the following statements is true?

$HClO_4$ is a stronger acid than $H_2SO_4$ due to which of the following reasons?
$1$. Oxidation state of $Cl$ in $HClO_4$ is $+7$ and that of $S$ in $H_2SO_4$ is $+6$.
$2$. $Cl$ is more electronegative than $S$.
$3$. $HClO_4$ is monobasic,whereas $H_2SO_4$ is dibasic.
$4$. $ClO_3$ part of $HClO_4$ can break $O-H$ bond more easily to liberate a proton than $SO_3$ part in $H_2SO_4$.

Arrange the following in the order of increasing basic character: $(NO_2, K_2O, ZnO)$