In the reaction $2Br^- + X_2 \to Br_2 + 2X^-$,$X_2$ is .......

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

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

Choose the correct answer from the options given below:

Which properties in a period indicate the chemical reactivity of elements?

Among the statements $(I-IV)$,the correct ones are:
$(I)$ $Be$ has smaller atomic radius compared to $Mg$.
$(II)$ $Be$ has higher ionization enthalpy than $Al$.
$(III)$ Charge/radius ratio of $Be$ is greater than that of $Al$.
$(IV)$ Both $Be$ and $Al$ form mainly covalent compounds.

The correct set that contains all kinds (basic, acidic, amphoteric, and neutral) of oxides is:

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R.$
Assertion $A :$ Metallic character decreases and non-metallic character increases on moving from left to right in a period.
Reason $R :$ It is due to increase in ionisation enthalpy and decrease in electron gain enthalpy,when one moves from left to right in a period.
In the light of the above statements,choose the most appropriate answer from the options given below :