JEE Main Previous Year Questions (2025): Co-ordination Compounds

 Page 1


JEE Main Previous Year Questions 
(2025): Co-ordination Compounds 
Q1: The complex of ????
?? +
 ion and dimethyl glyoxime contains ____ number of Hydrogen 
(H) atoms. 
JEE Main 2025 (Online) 22nd January Evening Shift 
Ans: 14 
Solution: 
Ni
2+
 with (dmg) forms [ Ni(dmg)
2
]
2+
 having 2 H -Bonds as shown : 
The no. of H atoms =14 
 
 
Q2: Total number of molecules/species from following which will be paramagnetic is 
____. 
?? ?? ,?? ?? +
,?? ?? -
,???? ,????
?? ,???? ,?? ?? [???????? ?? ],[???? (????
?? )
?? ]????
?? , ?? ?? [?? ??(???? )
?? ] 
JEE Main 2025 (Online) 28th January Evening Shift 
Ans: 6 
Solution: 
To determine which molecules or species are paramagnetic, we need to identify those with 
unpaired electrons. Here's the analysis: 
O
2
 : This molecule has 2 unpaired electrons as predicted by the Molecular Orbital Theory (MOT), 
making it paramagnetic. 
O
2
+
: This ion has 1 unpaired electron according to MOT, which also makes it paramagnetic. 
O
2
-
: This ion contains 1 unpaired electron as determined by MOT, indicating it is paramagnetic. 
NO: As a species with an odd number of electrons, NO has unpaired electrons, making it 
paramagnetic. 
Page 2


JEE Main Previous Year Questions 
(2025): Co-ordination Compounds 
Q1: The complex of ????
?? +
 ion and dimethyl glyoxime contains ____ number of Hydrogen 
(H) atoms. 
JEE Main 2025 (Online) 22nd January Evening Shift 
Ans: 14 
Solution: 
Ni
2+
 with (dmg) forms [ Ni(dmg)
2
]
2+
 having 2 H -Bonds as shown : 
The no. of H atoms =14 
 
 
Q2: Total number of molecules/species from following which will be paramagnetic is 
____. 
?? ?? ,?? ?? +
,?? ?? -
,???? ,????
?? ,???? ,?? ?? [???????? ?? ],[???? (????
?? )
?? ]????
?? , ?? ?? [?? ??(???? )
?? ] 
JEE Main 2025 (Online) 28th January Evening Shift 
Ans: 6 
Solution: 
To determine which molecules or species are paramagnetic, we need to identify those with 
unpaired electrons. Here's the analysis: 
O
2
 : This molecule has 2 unpaired electrons as predicted by the Molecular Orbital Theory (MOT), 
making it paramagnetic. 
O
2
+
: This ion has 1 unpaired electron according to MOT, which also makes it paramagnetic. 
O
2
-
: This ion contains 1 unpaired electron as determined by MOT, indicating it is paramagnetic. 
NO: As a species with an odd number of electrons, NO has unpaired electrons, making it 
paramagnetic. 
NO
2
 : This molecule is also an odd-electron species, which means it has unpaired electrons and 
is paramagnetic. 
K
2
[NiCl
4
] : In this compound, Ni
2+
 (nickel with a +2 oxidation state) has an electron 
configuration of 3?? 8
. Given the presence of weak field ligands and a coordination number of 4 , 
this forms a tetrahedral complex. As a result, it is paramagnetic with 2 unpaired electrons. 
Thus, the paramagnetic species in the provided list are O
2
,O
2
+
,O
2
-
,NO,NO
2
, and K
2
[NiCl
4
]. 
Q3: The spin only magnetic moment ( ?? ) value (B.M.) of the compound with strongest 
oxidising power among ????
?? ?? ?? ,?????? and VO is ____ B.M. (Nearest integer). 
JEE Main 2025 (Online) 28th January Evening Shift 
Ans: 5 
Solution: 
The compound with the strongest oxidizing power among Mn
2
O
3
,TiO, and VO is Mn
2
O
3
. This 
conclusion is based on the standard electrode potential (?? °
) value: ?? Mn+3/Mn
°
 
+2
=+1.57 V 
For Mn
3+
, the electronic configuration is ?? 4
. The spin-only magnetic moment ( ?? ) is calculated 
as follows: 
?? =v?? (?? +2) BM 
Where ?? is the number of unpaired electrons. Here, ?? =4 : 
?? =v4(4+2)=v24BM 
This calculates to approximately 4.89 BM, which rounds to an integer value of 5 BM . 
Q4: Consider the following low-spin complexes 
?? ?? [???? (????
?? )
?? ],?? ?? [???? (???? )
?? ],?? ?? [???? (???? )
?? ],????
?? [???? (???? )
?? ] and ????
?? [???? (???? )
?? ] 
The sum of the spin-only magnetic moment values of complexes having yellow colour 
is ____ B.M. (answer in nearest integer) 
JEE Main 2025 (Online) 29th January Evening Shift 
Ans: 0 
Solution: 
Given low-spin complexes: 
?? 3
[Co(NO
2
)
6
]- Yellow colour 
?? 4
[Fe(CN)
6
]- light yellow colour 
?? 3
[???? (???? )
6
]- bright red colour not yellow. 
?? ?? 2
[Fe(CN)
6
] - reddish brown color not yellow 
Zn
2
[Fe(NO
2
)
6
] - bluish-white colour not yellow 
?? 3
[Co(NO
2
)
6
] 
Oxidation state of ???? :+3 
Configuration: 
Page 3


JEE Main Previous Year Questions 
(2025): Co-ordination Compounds 
Q1: The complex of ????
?? +
 ion and dimethyl glyoxime contains ____ number of Hydrogen 
(H) atoms. 
JEE Main 2025 (Online) 22nd January Evening Shift 
Ans: 14 
Solution: 
Ni
2+
 with (dmg) forms [ Ni(dmg)
2
]
2+
 having 2 H -Bonds as shown : 
The no. of H atoms =14 
 
 
Q2: Total number of molecules/species from following which will be paramagnetic is 
____. 
?? ?? ,?? ?? +
,?? ?? -
,???? ,????
?? ,???? ,?? ?? [???????? ?? ],[???? (????
?? )
?? ]????
?? , ?? ?? [?? ??(???? )
?? ] 
JEE Main 2025 (Online) 28th January Evening Shift 
Ans: 6 
Solution: 
To determine which molecules or species are paramagnetic, we need to identify those with 
unpaired electrons. Here's the analysis: 
O
2
 : This molecule has 2 unpaired electrons as predicted by the Molecular Orbital Theory (MOT), 
making it paramagnetic. 
O
2
+
: This ion has 1 unpaired electron according to MOT, which also makes it paramagnetic. 
O
2
-
: This ion contains 1 unpaired electron as determined by MOT, indicating it is paramagnetic. 
NO: As a species with an odd number of electrons, NO has unpaired electrons, making it 
paramagnetic. 
NO
2
 : This molecule is also an odd-electron species, which means it has unpaired electrons and 
is paramagnetic. 
K
2
[NiCl
4
] : In this compound, Ni
2+
 (nickel with a +2 oxidation state) has an electron 
configuration of 3?? 8
. Given the presence of weak field ligands and a coordination number of 4 , 
this forms a tetrahedral complex. As a result, it is paramagnetic with 2 unpaired electrons. 
Thus, the paramagnetic species in the provided list are O
2
,O
2
+
,O
2
-
,NO,NO
2
, and K
2
[NiCl
4
]. 
Q3: The spin only magnetic moment ( ?? ) value (B.M.) of the compound with strongest 
oxidising power among ????
?? ?? ?? ,?????? and VO is ____ B.M. (Nearest integer). 
JEE Main 2025 (Online) 28th January Evening Shift 
Ans: 5 
Solution: 
The compound with the strongest oxidizing power among Mn
2
O
3
,TiO, and VO is Mn
2
O
3
. This 
conclusion is based on the standard electrode potential (?? °
) value: ?? Mn+3/Mn
°
 
+2
=+1.57 V 
For Mn
3+
, the electronic configuration is ?? 4
. The spin-only magnetic moment ( ?? ) is calculated 
as follows: 
?? =v?? (?? +2) BM 
Where ?? is the number of unpaired electrons. Here, ?? =4 : 
?? =v4(4+2)=v24BM 
This calculates to approximately 4.89 BM, which rounds to an integer value of 5 BM . 
Q4: Consider the following low-spin complexes 
?? ?? [???? (????
?? )
?? ],?? ?? [???? (???? )
?? ],?? ?? [???? (???? )
?? ],????
?? [???? (???? )
?? ] and ????
?? [???? (???? )
?? ] 
The sum of the spin-only magnetic moment values of complexes having yellow colour 
is ____ B.M. (answer in nearest integer) 
JEE Main 2025 (Online) 29th January Evening Shift 
Ans: 0 
Solution: 
Given low-spin complexes: 
?? 3
[Co(NO
2
)
6
]- Yellow colour 
?? 4
[Fe(CN)
6
]- light yellow colour 
?? 3
[???? (???? )
6
]- bright red colour not yellow. 
?? ?? 2
[Fe(CN)
6
] - reddish brown color not yellow 
Zn
2
[Fe(NO
2
)
6
] - bluish-white colour not yellow 
?? 3
[Co(NO
2
)
6
] 
Oxidation state of ???? :+3 
Configuration: 
Cod  
7
?? 2
 
?? ?? 3+
?? 6
 
3(+1)+?? +6(-1)=0 
3+?? -6=0 
?? =6-3=+3 
For low-spin d
6
 configuration, no unpaired electrons are present : 
N N N   
 
spin-only magnetic moment, ?? =v?? (?? +2) 
?? =0,?? =0 
This complex shows yellow colour (bright yellow) 
?? 4
[???? (???? )
6
] 
Oxidation state of ???? :+2 
4(+1)+?? +6(-1)=0 
4+?? -6=0 
?? =6-4=+2 
Configuration: 
???? ?? 6
?? 2
 
?? ?? +2
?? 6
 
?? =0 
For low-spin d
6
 configuration, no unpaired electrons are present : 
 
 
This complex shows yellow colour (light yellow) 
?? 3
[???? (???? )
6
] 
Oxidation state of ???? :+3 
3(+1)+?? +6(-1)=0 
3+?? -6=0 
?? =6-3=+3 
Configuration: 
???? ?? 6
?? 2
 
?? ?? +2
?? 5
 
low spin d
5
 
 
 
One unpaired electron is present. 
Spin-only magnetic moment, ?? =v?? (?? +2) 
?? ( number of unpaired electrons )=1 
Page 4


JEE Main Previous Year Questions 
(2025): Co-ordination Compounds 
Q1: The complex of ????
?? +
 ion and dimethyl glyoxime contains ____ number of Hydrogen 
(H) atoms. 
JEE Main 2025 (Online) 22nd January Evening Shift 
Ans: 14 
Solution: 
Ni
2+
 with (dmg) forms [ Ni(dmg)
2
]
2+
 having 2 H -Bonds as shown : 
The no. of H atoms =14 
 
 
Q2: Total number of molecules/species from following which will be paramagnetic is 
____. 
?? ?? ,?? ?? +
,?? ?? -
,???? ,????
?? ,???? ,?? ?? [???????? ?? ],[???? (????
?? )
?? ]????
?? , ?? ?? [?? ??(???? )
?? ] 
JEE Main 2025 (Online) 28th January Evening Shift 
Ans: 6 
Solution: 
To determine which molecules or species are paramagnetic, we need to identify those with 
unpaired electrons. Here's the analysis: 
O
2
 : This molecule has 2 unpaired electrons as predicted by the Molecular Orbital Theory (MOT), 
making it paramagnetic. 
O
2
+
: This ion has 1 unpaired electron according to MOT, which also makes it paramagnetic. 
O
2
-
: This ion contains 1 unpaired electron as determined by MOT, indicating it is paramagnetic. 
NO: As a species with an odd number of electrons, NO has unpaired electrons, making it 
paramagnetic. 
NO
2
 : This molecule is also an odd-electron species, which means it has unpaired electrons and 
is paramagnetic. 
K
2
[NiCl
4
] : In this compound, Ni
2+
 (nickel with a +2 oxidation state) has an electron 
configuration of 3?? 8
. Given the presence of weak field ligands and a coordination number of 4 , 
this forms a tetrahedral complex. As a result, it is paramagnetic with 2 unpaired electrons. 
Thus, the paramagnetic species in the provided list are O
2
,O
2
+
,O
2
-
,NO,NO
2
, and K
2
[NiCl
4
]. 
Q3: The spin only magnetic moment ( ?? ) value (B.M.) of the compound with strongest 
oxidising power among ????
?? ?? ?? ,?????? and VO is ____ B.M. (Nearest integer). 
JEE Main 2025 (Online) 28th January Evening Shift 
Ans: 5 
Solution: 
The compound with the strongest oxidizing power among Mn
2
O
3
,TiO, and VO is Mn
2
O
3
. This 
conclusion is based on the standard electrode potential (?? °
) value: ?? Mn+3/Mn
°
 
+2
=+1.57 V 
For Mn
3+
, the electronic configuration is ?? 4
. The spin-only magnetic moment ( ?? ) is calculated 
as follows: 
?? =v?? (?? +2) BM 
Where ?? is the number of unpaired electrons. Here, ?? =4 : 
?? =v4(4+2)=v24BM 
This calculates to approximately 4.89 BM, which rounds to an integer value of 5 BM . 
Q4: Consider the following low-spin complexes 
?? ?? [???? (????
?? )
?? ],?? ?? [???? (???? )
?? ],?? ?? [???? (???? )
?? ],????
?? [???? (???? )
?? ] and ????
?? [???? (???? )
?? ] 
The sum of the spin-only magnetic moment values of complexes having yellow colour 
is ____ B.M. (answer in nearest integer) 
JEE Main 2025 (Online) 29th January Evening Shift 
Ans: 0 
Solution: 
Given low-spin complexes: 
?? 3
[Co(NO
2
)
6
]- Yellow colour 
?? 4
[Fe(CN)
6
]- light yellow colour 
?? 3
[???? (???? )
6
]- bright red colour not yellow. 
?? ?? 2
[Fe(CN)
6
] - reddish brown color not yellow 
Zn
2
[Fe(NO
2
)
6
] - bluish-white colour not yellow 
?? 3
[Co(NO
2
)
6
] 
Oxidation state of ???? :+3 
Configuration: 
Cod  
7
?? 2
 
?? ?? 3+
?? 6
 
3(+1)+?? +6(-1)=0 
3+?? -6=0 
?? =6-3=+3 
For low-spin d
6
 configuration, no unpaired electrons are present : 
N N N   
 
spin-only magnetic moment, ?? =v?? (?? +2) 
?? =0,?? =0 
This complex shows yellow colour (bright yellow) 
?? 4
[???? (???? )
6
] 
Oxidation state of ???? :+2 
4(+1)+?? +6(-1)=0 
4+?? -6=0 
?? =6-4=+2 
Configuration: 
???? ?? 6
?? 2
 
?? ?? +2
?? 6
 
?? =0 
For low-spin d
6
 configuration, no unpaired electrons are present : 
 
 
This complex shows yellow colour (light yellow) 
?? 3
[???? (???? )
6
] 
Oxidation state of ???? :+3 
3(+1)+?? +6(-1)=0 
3+?? -6=0 
?? =6-3=+3 
Configuration: 
???? ?? 6
?? 2
 
?? ?? +2
?? 5
 
low spin d
5
 
 
 
One unpaired electron is present. 
Spin-only magnetic moment, ?? =v?? (?? +2) 
?? ( number of unpaired electrons )=1 
So, ?? =v?? (?? +2) 
=v1×3 
=v3 
=1.732BM 
Colour of the complex is not yellow. 
Cu
2
[Fe(CN)
6
],Cu
2+
 and [Fe(CN)
6
]
4-
 
?? +6(-1)=-4 
?? =-4+6 
=+2 
Oxidation state of ???? :+2 
Configuration: 
???? ?? 6
?? 2
 
?? ?? 2+
?? 6
 
For low-spin d
6
 configuration, no unpaired electrons are present 
?? ?? ??   
 
?? =0,?? =v?? (?? +2)=0 
Colour of the complex is not yellow. 
?? ?? 2
[???? (???? )
6
] 
[Fe(CN)
6
]
4-
 and Zn
2+
 
?? +6(-1)=-4 
?? =-4+6=+2 
Oxidation state of ???? :+2 
Configuration: 
???? ?? 6
?? 2
 
?? ?? 2+
?? 6
 
For low-spin d
6
 configuration, no unpaired electrons are present. 
 
 
 
?? =0,?? =v?? (?? +2)=0 
Colour of the complex is not yellow 
The complexes having yellow colour are ?? 3
[Co(NO
2
)
6
] and ?? 4
[Fe(CN)
6
] 
The sum of the spin-only magnetic moment values of complexes having yellow colour is 0 (zero). 
Q5: A transition metal ( M ) among ???? ,???? ,???? and Fe has the highest standard 
electrode potential (?? ?? +
/?? ?? +
). It forms a metal complex of the type [?? (???? )
?? ]
?? -
. 
The number of electrons present in the ?? ?? orbital of the complex is ____ ? 
Page 5


JEE Main Previous Year Questions 
(2025): Co-ordination Compounds 
Q1: The complex of ????
?? +
 ion and dimethyl glyoxime contains ____ number of Hydrogen 
(H) atoms. 
JEE Main 2025 (Online) 22nd January Evening Shift 
Ans: 14 
Solution: 
Ni
2+
 with (dmg) forms [ Ni(dmg)
2
]
2+
 having 2 H -Bonds as shown : 
The no. of H atoms =14 
 
 
Q2: Total number of molecules/species from following which will be paramagnetic is 
____. 
?? ?? ,?? ?? +
,?? ?? -
,???? ,????
?? ,???? ,?? ?? [???????? ?? ],[???? (????
?? )
?? ]????
?? , ?? ?? [?? ??(???? )
?? ] 
JEE Main 2025 (Online) 28th January Evening Shift 
Ans: 6 
Solution: 
To determine which molecules or species are paramagnetic, we need to identify those with 
unpaired electrons. Here's the analysis: 
O
2
 : This molecule has 2 unpaired electrons as predicted by the Molecular Orbital Theory (MOT), 
making it paramagnetic. 
O
2
+
: This ion has 1 unpaired electron according to MOT, which also makes it paramagnetic. 
O
2
-
: This ion contains 1 unpaired electron as determined by MOT, indicating it is paramagnetic. 
NO: As a species with an odd number of electrons, NO has unpaired electrons, making it 
paramagnetic. 
NO
2
 : This molecule is also an odd-electron species, which means it has unpaired electrons and 
is paramagnetic. 
K
2
[NiCl
4
] : In this compound, Ni
2+
 (nickel with a +2 oxidation state) has an electron 
configuration of 3?? 8
. Given the presence of weak field ligands and a coordination number of 4 , 
this forms a tetrahedral complex. As a result, it is paramagnetic with 2 unpaired electrons. 
Thus, the paramagnetic species in the provided list are O
2
,O
2
+
,O
2
-
,NO,NO
2
, and K
2
[NiCl
4
]. 
Q3: The spin only magnetic moment ( ?? ) value (B.M.) of the compound with strongest 
oxidising power among ????
?? ?? ?? ,?????? and VO is ____ B.M. (Nearest integer). 
JEE Main 2025 (Online) 28th January Evening Shift 
Ans: 5 
Solution: 
The compound with the strongest oxidizing power among Mn
2
O
3
,TiO, and VO is Mn
2
O
3
. This 
conclusion is based on the standard electrode potential (?? °
) value: ?? Mn+3/Mn
°
 
+2
=+1.57 V 
For Mn
3+
, the electronic configuration is ?? 4
. The spin-only magnetic moment ( ?? ) is calculated 
as follows: 
?? =v?? (?? +2) BM 
Where ?? is the number of unpaired electrons. Here, ?? =4 : 
?? =v4(4+2)=v24BM 
This calculates to approximately 4.89 BM, which rounds to an integer value of 5 BM . 
Q4: Consider the following low-spin complexes 
?? ?? [???? (????
?? )
?? ],?? ?? [???? (???? )
?? ],?? ?? [???? (???? )
?? ],????
?? [???? (???? )
?? ] and ????
?? [???? (???? )
?? ] 
The sum of the spin-only magnetic moment values of complexes having yellow colour 
is ____ B.M. (answer in nearest integer) 
JEE Main 2025 (Online) 29th January Evening Shift 
Ans: 0 
Solution: 
Given low-spin complexes: 
?? 3
[Co(NO
2
)
6
]- Yellow colour 
?? 4
[Fe(CN)
6
]- light yellow colour 
?? 3
[???? (???? )
6
]- bright red colour not yellow. 
?? ?? 2
[Fe(CN)
6
] - reddish brown color not yellow 
Zn
2
[Fe(NO
2
)
6
] - bluish-white colour not yellow 
?? 3
[Co(NO
2
)
6
] 
Oxidation state of ???? :+3 
Configuration: 
Cod  
7
?? 2
 
?? ?? 3+
?? 6
 
3(+1)+?? +6(-1)=0 
3+?? -6=0 
?? =6-3=+3 
For low-spin d
6
 configuration, no unpaired electrons are present : 
N N N   
 
spin-only magnetic moment, ?? =v?? (?? +2) 
?? =0,?? =0 
This complex shows yellow colour (bright yellow) 
?? 4
[???? (???? )
6
] 
Oxidation state of ???? :+2 
4(+1)+?? +6(-1)=0 
4+?? -6=0 
?? =6-4=+2 
Configuration: 
???? ?? 6
?? 2
 
?? ?? +2
?? 6
 
?? =0 
For low-spin d
6
 configuration, no unpaired electrons are present : 
 
 
This complex shows yellow colour (light yellow) 
?? 3
[???? (???? )
6
] 
Oxidation state of ???? :+3 
3(+1)+?? +6(-1)=0 
3+?? -6=0 
?? =6-3=+3 
Configuration: 
???? ?? 6
?? 2
 
?? ?? +2
?? 5
 
low spin d
5
 
 
 
One unpaired electron is present. 
Spin-only magnetic moment, ?? =v?? (?? +2) 
?? ( number of unpaired electrons )=1 
So, ?? =v?? (?? +2) 
=v1×3 
=v3 
=1.732BM 
Colour of the complex is not yellow. 
Cu
2
[Fe(CN)
6
],Cu
2+
 and [Fe(CN)
6
]
4-
 
?? +6(-1)=-4 
?? =-4+6 
=+2 
Oxidation state of ???? :+2 
Configuration: 
???? ?? 6
?? 2
 
?? ?? 2+
?? 6
 
For low-spin d
6
 configuration, no unpaired electrons are present 
?? ?? ??   
 
?? =0,?? =v?? (?? +2)=0 
Colour of the complex is not yellow. 
?? ?? 2
[???? (???? )
6
] 
[Fe(CN)
6
]
4-
 and Zn
2+
 
?? +6(-1)=-4 
?? =-4+6=+2 
Oxidation state of ???? :+2 
Configuration: 
???? ?? 6
?? 2
 
?? ?? 2+
?? 6
 
For low-spin d
6
 configuration, no unpaired electrons are present. 
 
 
 
?? =0,?? =v?? (?? +2)=0 
Colour of the complex is not yellow 
The complexes having yellow colour are ?? 3
[Co(NO
2
)
6
] and ?? 4
[Fe(CN)
6
] 
The sum of the spin-only magnetic moment values of complexes having yellow colour is 0 (zero). 
Q5: A transition metal ( M ) among ???? ,???? ,???? and Fe has the highest standard 
electrode potential (?? ?? +
/?? ?? +
). It forms a metal complex of the type [?? (???? )
?? ]
?? -
. 
The number of electrons present in the ?? ?? orbital of the complex is ____ ? 
JEE Main 2025 (Online) 2nd April Morning Shift 
Ans: 1 
Solution: 
Co has highest standard electrode potential (M
+3
/M
+2
) among Mn,Cr,Co,Fe 
? Complex is [Co(CN)
6
]
4
 and its splitting is as follows. 
 
 
 
? electron in e
g
 orbital is one. 
 
Q6: The spin-only magnetic moment value of ?? ?? +
 ion formed among ???? ,???? ,???? and 
Cu that has the least enthalpy of atomisation is ____ . (in nearest integer) Here ?? is 
equal to the number of diamagnetic complexes among 
?? ?? [???????? ?? ],[???? (?? ?? ?? )
?? ]????
?? , ?? ?? [???? (???? )
?? ] and [???? (??????
?? )
?? ??] 
JEE Main 2025 (Online) 2nd April Evening Shift 
Ans: 0 
Solution: 
K
2
[NiCl
4
]?sp
3
, Paramagnetic 
[Zn(H
2
O)
6
]Cl
2
?sp
3
 d
2
, Diamagnetic 
K
3
[Mn(CN)
6
]?d
2
sp
3
, Paramagnetic 
[Cu(PPh
3
)
3
I]?sp
3
, Diamagnetic 
Hence the value of ?? is 2 
Least value of enthalpy of atomisation among Ni , 
Zn,Mn and Cu is of Zn 
Zn
+2
:-[Ar]3 d
10
 
?? =0 
Q7: The number of optical isomers exhibited by the iron complex (A) obtained from 
the following reaction is ____ . 
???????? ?? +?????? +?? ?? ?? ?? ?? ?? ? ?? 
JEE Main 2025 (Online) 3rd April Morning Shift