IIT-JEE 2011 · Paper 2 · Chemistry Q2

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ChemistrySingle correct+3 / -1Question 2 of 60

Among the following complexes (K-P),

$\ce{K3[Fe(CN)6]}$ (K), $\ce{[Co(NH3)6]Cl3}$ (L), $\ce{Na3[Co(oxalate)3]}$ (M), $\ce{[Ni(H2O)6]Cl2}$ (N), $\ce{K2[Pt(CN)4]}$ (O) and $\ce{[Zn(H2O)6](NO3)2}$ (P)

the diamagnetic complexes are

K, L, M, N

K, M, O, P

L, M, O, P

L, M, N, O

Answer and worked solution

Official answer: C

Count unpaired electrons.

Complex	Metal ion	Configuration	Unpaired
K: $\ce{[Fe(CN)6]^{3-}}$	$\ce{Fe^{3+}}$ , d⁵ low spin	$t_{2g}^5$	1
L: $\ce{[Co(NH3)6]^{3+}}$	$\ce{Co^{3+}}$ , d⁶ low spin	$t_{2g}^6$	0
M: $\ce{[Co(ox)3]^{3-}}$	$\ce{Co^{3+}}$ , d⁶ low spin	$t_{2g}^6$	0
N: $\ce{[Ni(H2O)6]^{2+}}$	$\ce{Ni^{2+}}$ , d⁸ octahedral	$t_{2g}^6e_g^2$	2
O: $\ce{[Pt(CN)4]^{2-}}$	$\ce{Pt^{2+}}$ , d⁸ square planar	all paired	0
P: $\ce{[Zn(H2O)6]^{2+}}$	$\ce{Zn^{2+}}$ , d¹⁰	all paired	0

Diamagnetic: L, M, O and P.

(C)

Topics:Magnetic properties and colour Crystal field theory

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IIT-JEE 2011 · Paper 2, Chemistry question 2