Similarity in chemical properties of the atoms of elements in a group of the Periodic table is most closely related to

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

The first $(\Delta_{i} H_{1})$ and the second $(\Delta_{i} H_{2})$ ionization enthalpies (in $kJ \ mol^{-1}$) and the $(\Delta_{eg} H)$ electron gain enthalpy (in $kJ \ mol^{-1}$) of a few elements are given below:

Elements	$\Delta_{i} H_{1}$	$\Delta_{i} H_{2}$	$\Delta_{eg} H$
$I$	$520$	$7300$	$-60$
$II$	$419$	$3051$	$-48$
$III$	$1681$	$3374$	$-328$
$IV$	$1008$	$1846$	$-295$
$V$	$2372$	$5251$	$+48$
$VI$	$738$	$1451$	$-40$

Which of the above elements is likely to be:
$(a)$ the least reactive element.
$(b)$ the most reactive metal.
$(c)$ the most reactive non-metal.
$(d)$ the least reactive non-metal.
$(e)$ the metal which can form a stable binary halide of the formula $MX_{2}$ $(X = \text{halogen})$.
$(f)$ the metal which can form a predominantly stable covalent halide of the formula $MX$ $(X = \text{halogen})$?

What is an amphoteric oxide?

With the help of the following reactions,arrange metals $A$,$B$,$D$,and $E$ in decreasing order of their reactivity:
$(I)$ $B + ANO_3 \to BNO_3 + A$
$(II)$ $A + HCl \to ACl + \frac{1}{2}H_2$
$(III)$ $D + ECl \to DCl + E$
$(IV)$ $D + HNO_3 \to H_2$ gas is not evolved

If the valence shell electronic configuration for an element is $ns^2 np^5$,this element will belong to the group of