jee main chemistry important questions | Coordination Compounds jee main questions FREE

Q 1 :

The correct statements from the following are: [2024]

A. The strength of anionic ligands can be explained by crystal field theory.

B. Valence bond theory does not give a quantitative interpretation of kinetic stability of coordination compounds.

C. The hybridization involved in the formation of ${[Ni {(CN)}_{4}]}^{2 -}$ complex is $d s p^{2}$ .

D. The number of possible isomer(s) of cis- ${[{PtCl}_{2} {(en)}_{2}]}^{2 +}$ is one.

Choose the correct answer from the options given below:

B, C only
A, C only
A, D only
B, D only

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(1)

(A) Crystal field theory helps us in arranging the ligands in increasing order of their crystal field splitting strength.

(B) Valence bond theory does not give a quantitative interpretation of the thermodynamic or kinetic stabilities of coordination compounds.

(C) ${[Ni {(CN)}_{4}]}^{2 -}$

Oxidation number of Ni = +2

${Ni}^{2 +} : {}_{18}{[Ar] 3 d^{8}}$

${CN}^{-}$ is a strong field ligand, hence it causes pairing of $3 d^{8}$ electrons, then causes $d s p^{2}$ hybridization using 3d, 4s, and 4p orbitals.

(D) cis- ${[{PtCl}_{2} {(en)}_{2}]}^{2 +}$ has a pair of enantiomers.

Q 2 :

$' X'$ is the number of acidic oxides among ${VO}_{2}, V_{2} O_{3}, {CrO}_{3}, V_{2} O_{5}$ and ${Mn}_{2} O_{7}$ . The primary valency of cobalt in ${[Co {(H_{2} {NCH}_{2} {CH}_{2} {NH}_{2})}_{3}]}_{2} {({SO}_{4})}_{3}$ is Y.

The value of X + Y is: [2025]

5
4
2
3

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(1)

Oxide	Nature
$V_{2} O_{3}$	Basic
${VO}_{2}$	Basic
$V_{2} O_{5}$	Amphoteric
${CrO}_{3}$	Acidic
${Mn}_{2} O_{7}$	Acidic, thus X = 2

Primary valency is oxidation state. Oxidation state of Co in ${[Co {(H_{2} {NCH}_{2} {CH}_{2} {NH}_{2})}_{3}]}_{2} {({SO}_{4})}_{3}$ is +3. So Y = 3. X + Y = 5.

Q 3 :

$' X'$ is the number of electrons in $t_{2 g}$ orbitals of the most stable complex ion among ${[Fe {({NH}_{3})}_{6}]}^{3 +}$ , ${[Fe {(Cl)}_{6}]}^{3 -}, {[Fe {(C_{2} O_{4})}_{3}]}^{3 -}$ and ${[Fe {(H_{2} O)}_{6}]}^{3 +}$ . The nature of oxide of vanadium of the type $V_{2} O_{x}$ is: [2025]

Acidic
Neutral
Basic
Amphoteric

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(4)

Because of chelation effect, ${[Fe {(C_{2} O_{4})}_{3}]}^{3 -}$ is most stable. As $C_{2} O_{4}^{2 -}$ is a weak field ligand, ${Fe}^{3 +}$ $(3 d^{5})$ in ${[Fe {(C_{2} O_{4})}_{3}]}^{3 -}$ splits as $t_{2 g}^{3} e_{g}^{2}$ . Thus, ${[Fe {(C_{2} O_{4})}_{3}]}^{3 -}$ has five unpaired electrons. $V_{2} O_{5}$ is amphoteric.

Q 4 :

Total number of molecules/species from the following which will be paramagnetic is _________.

$O_{2}, O_{2}^{+}, O_{2}^{-}, NO, {NO}_{2}, CO, K_{2} [{NiCl}_{4}], [Co {({NH}_{3})}_{6}] {Cl}_{3}, K_{2} [Ni {(CN)}_{4}]$ [2025]

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(6)

Species	Electronic configuration/structure	Magnetic nature
$O_{2}$	$σ 1 s^{2}, σ^{} 1 s^{2}, σ 2 s^{2}, σ^{} 2 s^{2}, σ 2 p_{z}^{2}, π 2 p_{x}^{2}, π 2 p_{y}^{2}, π^{} 2 p_{x}^{1}, π^{} 2 p_{y}^{1}$	Paramagnetic
$O_{2}^{+}$	$σ 1 s^{2}, σ^{} 1 s^{2}, σ 2 s^{2}, σ^{} 2 s^{2}, σ 2 p_{z}^{2}, π 2 p_{x}^{2}, π 2 p_{y}^{2}, π^{*} 2 p_{x}^{1}$	Paramagnetic
$O_{2}^{-}$	$σ 1 s^{2}, σ^{} 1 s^{2}, σ 2 s^{2}, σ^{} 2 s^{2}, σ 2 p_{z}^{2}, π 2 p_{x}^{2}, π 2 p_{y}^{2}, π^{} 2 p_{x}^{2}, π^{} 2 p_{y}^{1}$	Paramagnetic
$NO$	$σ 1 s^{2}, σ^{} 1 s^{2}, σ 2 s^{2}, σ^{} 2 s^{2}, σ 2 p_{z}^{2}, π 2 p_{x}^{2}, π 2 p_{y}^{2}, π^{*} 2 p_{x}^{1}$	Paramagnetic
${NO}_{2}$		Paramagnetic
$CO$	$σ 1 s^{2}, σ^{} 1 s^{2}, σ 2 s^{2}, π 2 p_{x}^{2}, π 2 p_{y}^{2}, σ 2 p_{z}, σ^{} 2 s^{2}$	Diamagnetic
$K_{2} [{NiCl}_{4}]$		Paramagnetic
$[Co {({NH}_{3})}_{6}] {Cl}_{3}$		Diamagnetic
$K_{2} [Ni {(CN)}_{4}]$		Diamagnetic

Q 5 :

A transition metal (M) among Mn, Cr, Co and Fe has the highest standard electrode potential $(M^{3 +} / M^{2 +})$ . It forms a metal complex of the type ${[M {(CN)}_{6}]}^{4 -}$ . The number of electrons present in the $e_{g}$ orbital of the complex is ________. [2025]

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(1)

Among Cr, Mn, Fe and Co, highest $M^{3 +} / M^{2 +}$ potential is of Co.

	Cr	Mn	Fe	Co
$M^{3 +} / M^{2 +}$ (in V)	–0.41	+1.57	+0.77	+1.97

Thus the complex is ${[Co {(CN)}_{6}]}^{4 -}$ .

Oxidation number of Co = +2, ${Co}^{2 +} = {}_{18}{[Ar]}$ $3 d^{7}$ . As ${CN}^{-}$ is a strong field ligand, $3 d^{7}$ in octahedral field splits as $t_{2 g}^{6} e_{g}^{1}$ . Number of electrons in $e_{g}$ is 1.

Q 6 :

$[Ni {({PPh}_{3})}_{2} {Cl}_{2}]$ is a paramagnetic complex. Identify the INCORRECT statements about this complex.

A. The complex exhibits geometrical isomerism.
B. The complex is white in colour.
C. The calculated spin-only magnetic moment of the complex is 2.84 BM.
D. The calculated CFSE (Crystal Field Stabilization Energy) of Ni in this complex is $- 0.8 Δ_{0} .$
E. The geometrical arrangement of ligands in this complex is similar to that in $Ni {(CO)}_{4} .$

Choose the correct answer from the options given below : [2026]

C, D and E Only
A, B and D Only
C and D Only
A and B Only

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(2)

$[Ni {({PPh}_{3})}_{2} {Cl}_{2}]$

$Given : Paramagnetic complex hence it must be tetrahedral so$

$Crystal field splitting :$

[IMAGE 183]

$(A) Tetrahedral complex does not show geometrical isomerism.$

$(B) Complex is blue in colour$

$(C) Calculated spin only magnetic moment of the complex is 2.84 B.M.$

$(D) C.F.S.E. = - 0.6 Δ_{t} (4) + 0.4 Δ_{t} (4)$

$= - 0.8 Δ_{t} (not - 0.8 Δ_{o})$

$(E) Ni {(CO)}_{4} is also tetrahedral$

$Hence only A, B, D correct.$

Topic Question Set

Q 2 :

$' X'$ is the number of acidic oxides among ${VO}_{2}, V_{2} O_{3}, {CrO}_{3}, V_{2} O_{5}$ and ${Mn}_{2} O_{7}$ . The primary valency of cobalt in ${[Co {(H_{2} {NCH}_{2} {CH}_{2} {NH}_{2})}_{3}]}_{2} {({SO}_{4})}_{3}$ is Y.

The value of X + Y is: [2025]

Q 3 :

$' X'$ is the number of electrons in $t_{2 g}$ orbitals of the most stable complex ion among ${[Fe {({NH}_{3})}_{6}]}^{3 +}$ , ${[Fe {(Cl)}_{6}]}^{3 -}, {[Fe {(C_{2} O_{4})}_{3}]}^{3 -}$ and ${[Fe {(H_{2} O)}_{6}]}^{3 +}$ . The nature of oxide of vanadium of the type $V_{2} O_{x}$ is: [2025]

Q 4 :

Total number of molecules/species from the following which will be paramagnetic is _________.

$O_{2}, O_{2}^{+}, O_{2}^{-}, NO, {NO}_{2}, CO, K_{2} [{NiCl}_{4}], [Co {({NH}_{3})}_{6}] {Cl}_{3}, K_{2} [Ni {(CN)}_{4}]$ [2025]

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Q 5 :

A transition metal (M) among Mn, Cr, Co and Fe has the highest standard electrode potential $(M^{3 +} / M^{2 +})$ . It forms a metal complex of the type ${[M {(CN)}_{6}]}^{4 -}$ . The number of electrons present in the $e_{g}$ orbital of the complex is ________. [2025]

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