JEE MAIN - Chemistry (2023 - 6th April Morning Shift - No. 1)

Given below are two statements, one is labelled as Assertion $$\mathbf{A}$$ and the other is labelled as Reason $$\mathbf{R}$$.

Assertion A: The spin only magnetic moment value for $$\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-}$$ is $$1.74 \mathrm{BM}$$, whereas for $$\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}$$ is $$5.92 \mathrm{BM}$$.

Reason $$\mathbf{R}$$ : In both complexes, $$\mathrm{Fe}$$ is present in +3 oxidation state.

In the light of the above statements, choose the correct answer from the options given below:

Both A and R are true and R is the correct explanation of A
A is true but R is false
A is false but R is true
Both A and R are true but R is NOT the correct explanation of A

Explanation

JEE Main 2023 (Online) 6th April Morning Shift Chemistry - Coordination Compounds Question 68 English Explanation
Unpaired electron $=1$

$$ \mu=\sqrt{\mathrm{n}(\mathrm{n}+2)}=\sqrt{1 \times 3}=1.74 \text { B.M. } $$

$\left[\mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{3+}$ No pairing because $\mathrm{H}_2 \mathrm{O}$ is WFL

Number of unpaired electrons $=5, \mu=5.92 \mathrm{BM}$

Assertion is true, Reason is true but not correct explanation.

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