JEE Advanced 2013 · Paper 1 · Chemistry Q28

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ChemistrySingle correct+2Question 28 of 60

Consider the following complex ions, P, Q and R.
$\mathbf P=\ce{[FeF6]^{3-}},\quad\mathbf Q=\ce{[V(H2O)6]^{2+}}\quad\text{and}\quad\mathbf R=\ce{[Fe(H2O)6]^{2+}}.$
The correct order of the complex ions, according to their spin-only magnetic moment values (in B.M.) is

R < Q < P

Q < R < P

R < P < Q

Q < P < R

Answer and worked solution

Official answer: B

Unpaired electrons (water and F⁻ are weak-field):

P: Fe³⁺, d⁵ high spin, 5 unpaired, μ = 5.92 BM
Q: V²⁺, d³, 3 unpaired, μ = 3.87 BM
R: Fe²⁺, d⁶ high spin, 4 unpaired, μ = 4.90 BM

Order: Q < R < P.

(B)

Topics:Magnetic properties and colour Crystal field theory

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JEE Advanced 2013 · Paper 1, Chemistry question 28