Match List-$I$ with List-$II$.

List-$I$ (Oxide)	List-$II$ (Nature)
$A. Cl_2O_7$	$I. Amphoteric$
$B. Na_2O$	$II. Basic$
$C. Al_2O_3$	$III. Neutral$
$D. N_2O$	$IV. Acidic$

Choose the correct answer from the options given below:

Which of the following is the correct order of gradually decreasing basic nature of the oxides?

Classify oxides and provide examples for each type.

$HClO_4$ 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 $H_2SO_4$.

Use the periodic table to answer the following questions.
$(a)$ Identify an element with five electrons in the outer subshell.
$(b)$ Identify an element that would tend to lose two electrons.
$(c)$ Identify an element that would tend to gain two electrons.
$(d)$ Identify the group having metal,non-metal,liquid as well as gas at room temperature.

Which pair of elements has the same number of electrons in their valence shell$:-$