JEE Main 2016 · 3 Apr · Shift 1 · Chemistry Q48

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ChemistrySingle correct+4 / -1Question 48 of 90

The pair having the same magnetic moment is :

[At. No. : Cr = 24, Mn = 25, Fe = 26, Co = 27]

\ce{[Cr(H2O)6]^2+}

and

\ce{[CoCl4]^2-}

\ce{[Cr(H2O)6]^2+}

and

\ce{[Fe(H2O)6]^2+}

\ce{[Mn(H2O)6]^2+}

and

\ce{[Cr(H2O)6]^2+}

\ce{[CoCl4]^2-}

and

\ce{[Fe(H2O)6]^2+}

Answer and worked solution

Official answer: B

High-spin aqua complexes: $\ce{Cr^2+}$ is $d^4$ and $\ce{Fe^2+}$ is $d^6$ , both with 4 unpaired electrons, so both have $\sqrt{24}$ BM. $\ce{Mn^2+}$ has 5 unpaired and tetrahedral $\ce{[CoCl4]^2-}$ ( $d^7$ ) has 3.

Topics:Magnetic properties and colour Crystal field theory

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JEE Main 2016 · 3 Apr · Shift 1, Chemistry question 48