1. CrO ₄²⁻ 2. MnO ₄^- 3. Cr ₂ O ₇²⁻ 4. MnO ₄²⁻

Answer: 4. MnO ₄²⁻ d-d transitions need partly filled d orbitals; paramagnetism needs unpaired electrons. mathrmCrO₄²⁻ : Cr(+6), d⁰ . MnO₄^- : Mn(+7), d⁰ . mathrmCr₂O₇²⁻ : Cr(+6), d⁰ . mathrmMnO₄²⁻ : Mn(+6), d¹ , one unpaired electron. Only manganate shows both.

Topic: Crystal field theory, colour and magnetic properties· Coordination Compounds

Which one of the following ions exhibits d-d transition and paramagnetism as well ?

1. CrO\(_4^{2-}\)

2. MnO\(_4^-\)

3. Cr\(_2\)O\(_7^{2-}\)

4. MnO\(_4^{2-}\)

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Answer: 4. MnO\(_4^{2-}\)

d-d transitions need partly filled d orbitals; paramagnetism needs unpaired electrons.

\(\mathrm{CrO_4^{2-}}\): Cr(+6), \(d^0\).
\(\mathrm{MnO_4^-}\): Mn(+7), \(d^0\).
\(\mathrm{Cr_2O_7^{2-}}\): Cr(+6), \(d^0\).
\(\mathrm{MnO_4^{2-}}\): Mn(+6), \(d^1\), one unpaired electron.

Only manganate shows both.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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Which one of the following ions exhibits d-d transition and paramagnetism as well ?

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