Chemical Reactivity Questions in English

(C) To identify the amphoteric oxides,we analyze each oxide in the list:
$1$. $CO$: Neutral oxide.
$2$. $B_2O_3$: Weakly acidic oxide.
$3$. $SnO_2$: Amphoteric oxide.
$4$. $PbO_2$: Amphoteric oxide.
$5$. $Ga_2O_3$: Amphoteric oxide.
$6$. $SnO$: Amphoteric oxide.
$7$. $PbO$: Amphoteric oxide.
$8$. $CO_2$: Acidic oxide.
The amphoteric oxides are $SnO_2, PbO_2, Ga_2O_3, SnO,$ and $PbO$.
Therefore,the total number of amphoteric oxides is $5$.

(B) The oxidizing power of halogens decreases down the group as the reduction potential decreases.
Fluorine $(F_2)$ is the strongest oxidizing agent,while Iodine $(I_2)$ is the weakest.
$A$ halogen with a higher reduction potential can displace a halide ion with a lower reduction potential from its salt solution.
Since the reduction potential of $Cl_2$ is lower than that of $F_2$,$Cl_2$ cannot oxidize $F^-$ to $F_2$.
Therefore,the reaction $Cl_2 + 2F^- \longrightarrow 2Cl^- + F_2$ is not spontaneous and does not occur.

(D) The element belonging to the $4^{th}$ period and $15^{th}$ group is arsenic $(As)$.
The outer electronic configuration of a $15^{th}$ group element is $ns^{2} np^{3}$.
Since arsenic belongs to the $4^{th}$ period,it has a filled $3d$ subshell as well.
Thus,the electronic configuration of $As$ is $[Ar] 3d^{10} 4s^{2} 4p^{3}$.
This configuration shows that it has completely filled $s$- and $d$-orbitals and a half-filled $p$-orbital.

(C) The basic character of oxides depends on the metallic character of the element.
Metallic character decreases from left to right across a period,so the basic character of oxides also decreases from left to right.
Metallic character increases down a group,so the basic character of oxides increases from top to bottom.
Therefore,the basic character of oxides decreases from left to right and increases from top to bottom.

(B) The correct set of oxides arranged in the order of basic,amphoteric,and acidic is $BaO, Al_{2}O_{3}, SO_{2}$.
$BaO$ is a metal oxide of an alkaline earth metal,which is strongly basic.
$Al_{2}O_{3}$ is a well-known amphoteric oxide,reacting with both acids and bases.
$SO_{2}$ is a non-metal oxide,which is acidic in nature.

(A) The basic character of metal oxides depends on the electropositivity of the metal.
As we move down a group,the metallic character increases,and as we move across a period from left to right,the metallic character decreases.
$K$ is an alkali metal (Group $1$),while $Ba$,$Ca$,and $Mg$ are alkaline earth metals (Group $2$).
Within Group $2$,the metallic character increases as we go down the group: $Mg < Ca < Ba$.
Since $K$ is more electropositive than the Group $2$ metals,$K_2O$ is the most basic.
Therefore,the correct decreasing order of basic character is $K_2O > BaO > CaO > MgO$.

(C) Metallic character increases down a group and decreases across a period from left to right. Among the given elements ($N$,$P$,$O$,$S$,$Cl$,$F$),$P$ (Phosphorus) is the most metallic as it is the furthest to the left and down in the periodic table compared to the others. Its valence shell configuration is $3s^2 3p^3$,so it has $5$ valence electrons.
$F$ (Fluorine) is the most electronegative and least metallic element in the list. Its valence shell configuration is $2s^2 2p^5$,so it has $7$ valence electrons.
Therefore,the number of valence electrons for the most metallic $(P)$ and least metallic $(F)$ elements are $5$ and $7$ respectively.

(C) Basic oxides are typically oxides of metals,such as $Na_2O$ and $K_2O$.
Acidic oxides are typically oxides of non-metals,such as $Cl_2O_7$.
Amphoteric oxides exhibit both acidic and basic properties,such as $Al_2O_3$ and $As_2O_3$.
Neutral oxides do not react with either acids or bases,such as $NO, N_2O$,and $CO$.
Option $C$ contains: $K_2O$ (Basic),$Cl_2O_7$ (Acidic),$As_2O_3$ (Amphoteric),and $NO$ (Neutral). Thus,it is the correct set.

(D) Statement $I$: $[Al_2O_3, Cr_2O_3]$ are both amphoteric. $[Cl_2O_7, Mn_2O_7]$ are both acidic. $[Na_2O]$ is basic,while $[V_2O_3]$ is amphoteric. $[CO, N_2O]$ are both neutral. Thus,only $3$ pairs have the same nature. Therefore,Statement $I$ is false.
Statement $II$: $Na_2O$ is a highly basic metallic oxide and $Cl_2O_7$ is a strongly acidic non-metallic oxide. Therefore,Statement $II$ is true.

(C) Metallic character is defined as the tendency of an element to lose electrons.
Metallic character increases as we move down a group and decreases as we move from left to right across a period.
The positions of the given elements in the periodic table are:
$P$ (Group $15$,Period $3$)
$Si$ (Group $14$,Period $3$)
$Mg$ (Group $2$,Period $3$)
$Na$ (Group $1$,Period $3$)
$Be$ (Group $2$,Period $2$)
Comparing these,$P$ is the least metallic (non-metal),followed by $Si$ (metalloid). Among the metals,$Be$ is less metallic than $Mg$ (since $Be$ is in Period $2$ and $Mg$ is in Period $3$ of the same group). $Na$ is the most metallic as it is in Group $1$.
Thus,the correct order of increasing metallic character is: $P < Si < Be < Mg < Na$.