Chemistry Q58 – NEET-UG 2026

Home Chemistry Coordination CompoundsQuestion #356

According to crystal field theory, the correct order of ligands with respect to their decreasing order of field strength is

Clue 1 of 3: Spectrochemical Series

The spectrochemical series is an experimentally determined series of ligands arranged in order of their increasing field strength.

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Ninja Strategy•Spectrochemical Series Extremes

Recognize that $CO$ is a strong field ligand and ${Cl}^{-}$ is a weak field ligand. This immediately eliminates options starting with ${Cl}^{-}$ and helps narrow down the choices.

🧠 Full Solution Path

Step 1: Recall the Spectrochemical Series✦ Active

The spectrochemical series lists ligands in order of their increasing crystal field splitting energy (field strength). A portion of the series, relevant to the given ligands, is:

I^{-} < {Br}^{-} < {Cl}^{-} < F^{-} < {OH}^{-} < H_{2} O < {NH}_{3} < en < {NO}_{2}^{-} < {CN}^{-} < CO

💡 Teacher's Secret Hint

Remember that $CO$ and ${CN}^{-}$ are strong field ligands, while halides are weak field ligands.

Step 2: Arrange Ligands in Decreasing Field Strength○ Expand

From the spectrochemical series, the order of the given ligands in decreasing field strength is:

CO > {NH}_{3} > H_{2} O > {Cl}^{-}

💡 Teacher's Secret Hint

Pay close attention to the relative positions of ${NH}_{3}$ and $H_{2} O$ as this is a common point of confusion.

Step 3: Match with Options○ Expand

Comparing this order with the given options, option (1) matches the correct decreasing order of ligand field strength.

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Chemistry Question 58 – NEET-UG 2026

Clue 1 of 3: Spectrochemical Series

🧠 Full Solution Path