Match List - I with List - II. List - I Chromium (III) Complexes (en = ethylene diamine) A. [Cr(CN)6]3- B. [CrF6]3- C. [Cr(H2O)6]3+ D. [Cr(en)3]3+ List - II Δo(cm-1) I. 15,060 II. 17,400 III. 22,300 IV. 26,600 Choose the correct answer from the options given below :

The correct answer is Option 4. Full mathematical solution steps and hints are accessible in the interactive StemCET workspace.

Chemistry Q62 – JEE-MAIN 2026

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Home Chemistry Coordination CompoundsQuestion #318

Match List - I with List - II.

\begin{array}{lcl} List - I & List - II \\ Chromium (III) Complexes & Δ_{o} ({cm}^{- 1}) \\ (en = ethylene diamine) \\ A. [C r (C N)_{6}]^{3 -} & I. 15, 060 \\ B. [C r F_{6}]^{3 -} & II. 17, 400 \\ C. [C r (H_{2} O)_{6}]^{3 +} & III. 22, 300 \\ D. [C r (e n)_{3}]^{3 +} & IV. 26, 600 \end{array}

Choose the correct answer from the options given below :

Clue 1 of 3: Spectrochemical Series

The magnitude of crystal field splitting energy ( $Δ_{o}$ ) depends on the nature of the ligand. Strong field ligands cause larger splitting, while weak field ligands cause smaller splitting.

🧠 Full Solution Path

Step 1: Determine Oxidation State and Ligand Field Strength✦ Active

All complexes are Chromium(III) complexes, meaning the central metal ion is $C r^{3 +}$ . The crystal field splitting energy ( $Δ_{o}$ ) for octahedral complexes depends on the ligand field strength. We need to arrange the given ligands ( $C N^{-}$ , $F^{-}$ , $H_{2} O$ , $e n$ ) according to the spectrochemical series from weakest to strongest field:

F^{-} < H_{2} O < e n < C N^{-}

Step 2: Order Complexes by Increasing

Δ_{o}

○ Expand

Based on the ligand field strength, the complexes will have increasing $Δ_{o}$ values in the following order:

[C r F_{6}]^{3 -} < [C r (H_{2} O)_{6}]^{3 +} < [C r (e n)_{3}]^{3 +} < [C r (C N)_{6}]^{3 -}

The given $Δ_{o}$ values in increasing order are: $15, 060 < 17, 400 < 22, 300 < 26, 600 {cm}^{- 1}$ .

💡 Teacher's Secret Hint

Remember that 'en' (ethylenediamine) is a bidentate ligand, but its position in the spectrochemical series is what matters for $Δ_{o}$ .

Step 3: Match Complexes to

Δ_{o}

Values○ Expand

Matching the ordered complexes with the ordered $Δ_{o}$ values:

\begin{array}{ll} B. [C r F_{6}]^{3 -} & \to I. 15, 060 {cm}^{- 1} \\ C. [C r (H_{2} O)_{6}]^{3 +} & \to II. 17, 400 {cm}^{- 1} \\ D. [C r (e n)_{3}]^{3 +} & \to III. 22, 300 {cm}^{- 1} \\ A. [C r (C N)_{6}]^{3 -} & \to IV. 26, 600 {cm}^{- 1} \end{array}

This corresponds to the matching: A-IV, B-I, C-II, D-III. Comparing this with the given options, option 4 is the correct match.

💡 Teacher's Secret Hint

Double-check the order of ligands and corresponding $Δ_{o}$ values to avoid common errors.

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Chemistry Question 62 – JEE-MAIN 2026

Clue 1 of 3: Spectrochemical Series

🧠 Full Solution Path