When a metal rod $M$ is dipped into an aqueous colourless concentrated solution of compound $N$,the solution turns light blue. Addition of aqueous $NaCl$ to the blue solution gives a white precipitate $O$. Addition of aqueous $NH_3$ dissolves $O$ and gives an intense blue solution.
$1.$ The metal rod $M$ is
$(A)$ $Fe$ $(B)$ $Cu$ $(C)$ $Ni$ $(D)$ $Co$
$2.$ The compound $N$ is
$(A)$ $AgNO_3$ $(B)$ $Zn(NO_3)_2$
$(C)$ $Al(NO_3)_3$ $(D)$ $Pb(NO_3)_2$
$3.$ The final solution contains
$(A)$ $[Pb(NH_3)_4]^{2+}$ and $[CoCl_4]^{2-}$
$(B)$ $[Al(NH_3)_4]^{3+}$ and $[Cu(NH_3)_4]^{2+}$
$(C)$ $[Ag(NH_3)_2]^{+}$ and $[Cu(NH_3)_4]^{2+}$
$(D)$ $[Ag(NH_3)_2]^{+}$ and $[Ni(NH_3)_6]^{2+}$
Give the answer for questions $1$,$2$ and $3$.

List-$I$ contains metal species and List-$II$ contains their properties.

List-$I$	List-$II$
$I$. $[Cr(CN)_6]^{4-}$	$P$. $t_{2g}$ orbitals contain $4$ electrons
$II$. $[RuCl_6]^{2-}$	$Q$. $\mu$ (spin-only) $= 4.9 \ BM$
$III$. $[Cr(H_2O)_6]^{2+}$	$R$. low spin complex ion
$IV$. $[Fe(H_2O)_6]^{2+}$	$S$. metal ion in $4+$ oxidation state
	$T$. $d^4$ species

[Given: Atomic number of $Cr = 24, Ru = 44, Fe = 26$] Match each metal species in List-$I$ with their properties in List-$II$,and choose the correct option.

Match List-$I$ with List-$II$ and select the correct option:

List-$I$	List-$II$
$(A). [Ag(CN)_2]^-$	$1. \text{Square planar, } 1.73 \, B.M.$
$(B). [Cu(CN)_4]^{3-}$	$2. \text{Linear, } 0 \, B.M.$
$(C). [Cu(CN)_6]^{4-}$	$3. \text{Octahedral, } 0 \, B.M.$
$(D). [Cu(NH_3)_4]^{2+}$	$4. \text{Tetrahedral, } 0 \, B.M.$
$(E). [Fe(CN)_6]^{4-}$	$5. \text{Octahedral, } 1.73 \, B.M.$

Which of the following statements is correct?

The number of ions present in $2 \ L$ of a solution of $1.6 \ M \ K_4[Fe(CN)_6]$ is:

The correct option(s) about entropy $(S)$ is(are)
$[R =$ gas constant, $F =$ Faraday constant, $T =$ Temperature $]$
$(A)$ For the reaction, $M_{(s)} + 2H^{+}_{(aq)} \rightarrow H_{2(g)} + M^{2+}_{(aq)}$, if $\frac{dE_{cell}}{dT} = \frac{R}{F}$, then the entropy change of the reaction is $R$ (assume that entropy and internal energy changes in entropy and internal energy are temperature independent).
$(B)$ The cell reaction, $Pt_{(s)} \mid H_2(g, 1 \ bar) \mid H^{+}(aq, 0.01 \ M) \parallel H^{+}(aq, 0.1 \ M) \mid H_2(g, 1 \ bar) \mid Pt_{(s)}$, is an entropy driven process.
$(C)$ For racemization of an optically active compound, $\Delta S > 0$.
$(D)$ $\Delta S > 0$, for $[Ni(H_2O)_6]^{2+} + 3en \rightarrow [Ni(en)_3]^{2+} + 6H_2O$ (where $en =$ ethylenediamine).