Verified Solution • 2025–26 Session moderate

QJEEAdv23Ch1275: JEE Advanced 2023 Chemistry - Class 12 JEEAdv23Ch1275 Solution: Match the electronic configurations in List-I with appropriate…

Match the electronic configurations in List-I with appropriate metal complex ions in List-II and choose the correct option.

[Atomic Number: Fe=26,Mn=25,Co=27\mathrm{Fe}=26, \mathrm{Mn}=25, \mathrm{Co}=27 ]

List - I List - II
(P) t2g6eg0t_{2 g}^6 e_g^0 (1) [Fe(H2O)6]2+\left[\mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}
(Q) t2g3eg2t_{2 g}^3 e_g^2 (2) [Mn(H2O)6]2+\left[\mathrm{Mn}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}
(R) e2t23\mathrm{e}^2 \mathrm{t}_2^3 (3) [Co(NH3)6]3+\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}
(S) t2g4eg2t_{2 g}^4 e_g^2 (4) [FeCl4]−\left[\mathrm{FeCl}_4\right]^{-}
(5) [CoCl4]2−\left[\mathrm{CoCl}_4\right]^{2-}

Multiple Choice Options

  • A P→1;Q→4;R→2;S→3\mathrm{P} \rightarrow 1 ; \mathrm{Q} \rightarrow 4 ; \mathrm{R} \rightarrow 2 ; \mathrm{S} \rightarrow 3
  • B P→1;Q→2;R→4;S→5P \rightarrow 1 ; \mathrm{Q} \rightarrow 2 ; \mathrm{R} \rightarrow 4 ; \mathrm{S} \rightarrow 5
  • C P→3;Q→2;R→5;S→1\mathrm{P} \rightarrow 3 ; \mathrm{Q} \rightarrow 2 ; \mathrm{R} \rightarrow 5 ; \mathrm{S} \rightarrow 1
  • D P→3;Q→2;R→4;S→1\mathrm{P} \rightarrow 3 ; \mathrm{Q} \rightarrow 2 ; \mathrm{R} \rightarrow 4 ; \mathrm{S} \rightarrow 1

Step-by-Step Verified Solution

1.

amp;[Fe(H2O)6]2+amp;Fe(26)⟶3 d64 s2amp;Fe2+⟶3 d6,H2O is a weak field ligand. \begin{aligned}& {\left[\mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}} \\\\& \mathrm{Fe}(26) \longrightarrow 3 \mathrm{~d}^6 4 \mathrm{~s}^2 \\\\& \mathrm{Fe}^{2+} \longrightarrow 3 \mathrm{~d}^6, \mathrm{H}_2 \mathrm{O} \text { is a weak field ligand. }\end{aligned}

So, the pairing does not take place.

JEE Advanced 2023 Paper 1 Online Chemistry - Coordination Compounds Question 7 English Explanation 1
2.

amp;[Mn(H2O)6]2+amp;Mn(25)⟶3 d54 s2amp;Mn2+⟶3 d5,H2O is a weak field ligand. \begin{aligned}& {\left[\mathrm{Mn}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}} \\\\& \mathrm{Mn}(25) \longrightarrow 3 \mathrm{~d}^5 4 \mathrm{~s}^2 \\\\& \mathrm{Mn}^{2+} \longrightarrow 3 \mathrm{~d}^5, \mathrm{H}_2 \mathrm{O} \text { is a weak field ligand. }\end{aligned}

So, the pairing does not take place.

JEE Advanced 2023 Paper 1 Online Chemistry - Coordination Compounds Question 7 English Explanation 2

3.

[CO(NH3)6]3+\left[\mathrm{CO}\left(\mathrm{NH}_3\right)_6\right]^{3+}

CO3+⟶[Ar]3 d6\mathrm{CO}^{3+} \longrightarrow[\mathrm{Ar}] 3 \mathrm{~d}^6

NH3\mathrm{NH}_3 is a strong field ligand. So, the pairing takes place.

JEE Advanced 2023 Paper 1 Online Chemistry - Coordination Compounds Question 7 English Explanation 3
4.

amp;[FeCl4]−amp;x+4(−1)=−1amp;x=+3amp;Fe(26)⟶3 d64 s2amp;Fe+3⟶[Ar]3 d5\begin{aligned}& \begin{aligned}{\left[\mathrm{FeCl}_4\right]^{-} }\end{aligned} \\\\& x+4(-1)=-1 \\\\& x=+3 \\\\& \mathrm{Fe}(26) \longrightarrow 3 \mathrm{~d}^6 4 \mathrm{~s}^2 \\\\& \mathrm{Fe}^{+3} \longrightarrow[\mathrm{Ar}] 3 \mathrm{~d}^5\end{aligned}

FeCl4\mathrm{FeCl}_4 is tetrahedral complex.

JEE Advanced 2023 Paper 1 Online Chemistry - Coordination Compounds Question 7 English Explanation 4
amp; 5. [COCl4]2−amp;CO⟶3 d74 s2amp;CO2+⟶3 d7\begin{aligned} & \text { 5. }\left[\mathrm{COCl}_4\right]^{2-} \\\\ & \mathrm{CO} \longrightarrow 3 \mathrm{~d}^7 4 \mathrm{~s}^2 \\\\ & \mathrm{CO}^{2+} \longrightarrow 3 \mathrm{~d}^7 \end{aligned}

JEE Advanced 2023 Paper 1 Online Chemistry - Coordination Compounds Question 7 English Explanation 5
∴P→3,Q→2,R→4, S→1\therefore \mathrm{P} \rightarrow 3, \mathrm{Q} \rightarrow 2, \mathrm{R} \rightarrow 4, \mathrm{~S} \rightarrow 1

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