COORDINATION COMPOUNDS (d) Write the hybridization and magnetic character of the complex [Ni(CO)4] on

Previous year CBSE questions the basis of valence bond theory. [Atomic No.: Ni = 28]
CBSE 2024 (e) Out of [CoF6]3– and [Co(C2O4)3]3– , which one complex is:
1. On adding AgNO3 solution to 1 mole of complex NiCl2. 4NH3, two moles of AgCl
(i) more stable ? (ii) the high spin complex ?
are formed. The secondary valency of Ni in the complex will be:
(f) What is the difference between an ambidentate ligand and bidentate ligand?
(A) 4 (B) 2 (C) 3 (D) 6
(g) Write the electronic configuration of d5 in terms of t2g and eg in an
2. On adding AgNO3 solution to 1 mole of CoCl3 . 4NH3, one mole of AgCl is
octahedral field when: (i) ∆o > P, and (ii) ∆o < P
precipitated. The secondary valency of Co is :
13. Answer any five of the following :
(A) 6 (B) 4 (C) 3 (D) 7
(a) How is the crystal field splitting energy for octahedral complex (∆o) related to
3. Ligand EDTA4– is an example of a:
that of tetrahedral complex (∆t)?
(A) Monodentate ligand (B) Didentate ligand
(b) Write the IUPAC name of the following complex: [PtCl2(en)2] (NO3)2
(C) Tridentate ligand (D) Polydentate ligand
(c) Write the geometry and magnetic behaviour of the complex [Ni(CO)4] on the
4. Which of the following ligand forms chelate complex?
−¿¿
basis of Valency Bond Theory (VBT).
2−¿¿
(A) C 2 O 4 (B) Cl– (C) NO 2 (D) NH3 (d) What type of isomerism is shown by the complex[Co(NH3)6] [Cr(CN)6]?
5. Which of the following ligands is an ambidentate ligand? (e) For the coordination compound on the basis of crystal field theory, write
(A) CO (B) SCN– (C) NH3 (D) H2O the electronic configuration for d4 ion if ∆o < P. Is the coordination compound
6. The coordination number of Co in [Co(en)3]3+ is : a high spin or low spin complex?
(A) 3 (B) 4 (C) 5 (D) 6 (f) Out of [Co(NH3)6]3+ and [Co(NH3)4Cl2]+, which complex is heteroleptic and
7. Which one of the following complexes is non-ionisable? why ?
(A) [Co(NH3)3 Cl3] (B) [Co(NH3)4 Cl2] Cl (g) Draw the structures of optical isomers of [PtCl2(en)2]2+.
(C) [Co(NH3)5 Cl] Cl2(D) [Co(NH3)6] Cl3
8. The type of isomerism shown by the complex [CoCl2(en)2]+ is : 14. (a) Write the formula for the following coordination compound:
(A) Linkage isomerism (B) Geometrical isomerism Potassium tetrahydroxidozincate (II)
(C) Coordination isomerism (D) Ionization isomerism (b) Arrange the following complexes in the increasing order of conductivity of their
9. Which of the following ligands can show linkage isomerism in a coordination solution:
compound? [Cr(NH3)5Cl]Cl2, [Cr(NH3)3Cl3], [Cr(NH3)6]Cl3
2−¿ ¿ −¿¿ 2−¿¿ (c) Identify the type of isomerism exhibited by the following complexes:
(A) NH3 (B) SO 4 (C) NO 2 (D) C 2 O 4
(i) [Co(NH3)5NO2]2+ (ii) [Co(en)3]Cl3
10. Which one of the following hybrid states is associated with low spin complex?
15. The Valence Bond Theory (VBT) explains the formation, magnetic
(A) sp3d (B) sp3 (C) sp3d2 (D) d2 sp3
behaviour and geometrical shapes of coordination compounds whereas ‘The Crystal
11. Which of the following is diamagnetic in nature?
Field Theory’ for coordination compounds is based on the effect of different crystal
(A) Co3+, octahedral complex with strong field ligand
fields (provided by ligands taken as point charges), on the degeneracy of d-orbital
(B) Co3+, octahedral complex with weak field ligand
energies of the central metal atom/ion. The splitting of the d-orbitals provides
(C) Co3+, in a square planar complex
different electronic arrangements in strong and weak crystal fields. The crystal field
(D) Co3+, in a tetrahedral complex
theory attributes the colour of the coordination compounds to d-d transition of the
[ Atomic number : Co = 27 ]
electron. Coordination compounds find extensive applications in metallurgical
12. Attempt any five of the following:
processes, analytical and medicinal chemistry.
(a) Write the IUPAC name of the complex:
Answer the following questions:
[Co(H2O)(CN)(en)2]2+
(a) What is crystal field splitting energy?
(b) Why is geometrical isomerism not possible in tetrahedral complexes having two
(b) Give reason for the violet colour of the complex [Ti(H2O)6]3+ on the basis of
different types of unidentate ligands coordinated with the central metal ion?
crystal field theory.
(c) Arrange the following complex ions in increasing order of their crystal field
(c) [Cr(NH3)6]3+ is paramagnetic while [Ni(CN)4]2– is diamagnetic.
splitting energy (∆o): [Co(NH3)6]3+, [CoF6]3– , [Co(CN)6]3–
 Explain why. [Atomic No.: Cr = 24, Ni = 28] 2 (b) The complex [Co(NH3)5(NO2)]Cl2 is red in colour. Give IUPAC name of its
OR linkage isomer.
(c) Explain why [Fe(CN)6]3– is an inner orbital complex, whereas 15. (a) On the basis of crystal field theory write the electronic configuration for d 5 ion
[Fe(H2O)6]3+ is an outer orbital complex. [Atomic No.: Fe = 26] with a strong field ligand for which ∆0 > P.
(b) [Ni(CO)4] has tetrahedral geometry while [Ni(CN)4]2– has square
CBSE 2023 planar yet both exhibit dimagnetism. Explain. [ Ni = 28]
1. How many ions are produced in the solution from the complex 16. (a) Write the IUPAC names of the following :
[Ni(NH3)6]Cl2? (i) [Co(NH3)5(ONO)]2+ (ii) K2[NiCl4]
(a) 4 (b) 3 (c) 2 (d) 5 OR
2. Which of the following species is not expected to be a ligand? (b) (i) What is a chelate complex ? Give one example.
+¿¿
(a) CO (b) NH 4 (c) NH3 (d) H2O (ii) What are heteroleptic complexes ? Give one example.
3. [Co(NH3)5NO3]SO4 and [Co(NH3)5SO4]NO3 exhibit : 17. Answer any three of the following questions :
(a) linkage isomerism (b) ionization isomerism (a) Explain the type of hybridization in [Fe(CN)6]3- on the basis of
(c) optical isomerism(d) coordination isomerism valence bond theory. (Given : Atomic number of Fe = 26)
4. The magnetic moment of [NiCl4]2– (b) Draw the geometrical isomers of [PtCl2(en)2]2+ ion.
(a) 1.82 BM (b) 2.82 BM (c) 4.42 BM (d) 5.46 BM (c) [NiCl4]2- is paramagnetic while [Ni(CO)4] is diamagnetic though
[Atomic number: Ni = 28] both are tetrahedral. Why?
5. Which of the following is the most stable complex species ? (d) Name the type of isomerism when ambidentate ligands are
(a) [Fe(C2O4)3]3- (b) [Fe(CN)6]3- (c) [Fe(CO)5] (d) [Fe(H2O)6]3+ attached to central metal ion. Give one example of ambidentate
6. The compounds [Co(SO4) (NH3)5] Br and [Co(Br) (NH3)5] SO4 represent ligand.
(a) optical isomerism (b) linkage isomerism 18.In coordination compounds, metals show two types of linkages, primaryand
(c) ionisation isomerism (d) coordination isomerism secondary. Primary valencies are ionisable and are satisfied bynegatively charged
7. The formula of the complex dichloridobis (ethane –1, 2-diamine) platinum(IV) ions. Secondary valencies are non-ionisable and aresatisfied by neutral or negative
nitrate is ions having lone pair of electrons. Primary valencies are non-directional while
(a) [Pt Cl2(en)2 (NO3)2] (b) [Pt Cl2(en)2] (NO3)2 secondary valencies decide the shape of the complexes.
(c) [Pt Cl2(en)2 (NO3)]NO3 (d) [Pt (en)2 (NO3)2]Cl2 (i) If PtCl2 . 2NH3 does not react with AgNO3, what will be its formula?
8. The oxidation state of Fe in [Fe(CO)5] is (ii) What is the secondary valency of [Co(en)3]3+ ?
(a) + 2 (b) 0 (c) + 3 (d) + 5 (iii) (1) Write the formula of Iron(III)hexacyanidoferrate(II).
9. In which of the following does the central atom exhibit an oxidation state of +3? (2) Write the IUPAC name of [Co(NH3)5Cl] Cl2.
(a) K2[Ni(CN)4] (b) K4[Fe(CN)6] (c) [Fe(C2O4)3]3- (d) [Cu(NH3)4]2+ OR
3–
10. Assertion (A): Trans [Cr Cl2(ox)2] shows optical isomerism. (iii) Write the hybridization and magnetic behaviour of [Ni(CN)4]2- .
Reason (R): Optical isomerism is common in octahedral complexes involving [Atomic number : Ni = 28]
didentate ligands. 19. (a) Draw the geometrical isomers of [Co(en)2Cl2]2+. Which geometrical isomer of
11. Assertion (A): EDTA is a hexadentate ligand. [Co(en)2Cl2]2+ is not optically active and why ?
Reason (R): EDTA has 2 nitrogen and 4 oxygen donor atoms. (b) Write the hybridisation and magnetic behaviour of [CoF6]3–.
12. Assertion (A) : Low spin tetrahedral complexes are rarely observed. [Given : Atomic number of Co = 27]
Reason (R) : Crystal field splitting energy is less than pairing energy 20. Coordination compounds are widely present in the minerals, plant and animal
for tetrahedral complexes. worlds and are known to play many important functions in the area of analytical
13. Write IUPAC names of the following coordination entities : chemistry, metallurgy, biological systems and medicine. Alfred Werner’s Theory
(a) [Co(NH3)4Cl(NO2)]Cl (b) [PtCl2(en)2]2+ postulated the use of two types of linkages (primary and secondary), by a metal
14. (a) Which of the following species cannot act as a ligand? Give reason. atom/ion in a coordination compound. He predicted the geometrical shapes of a
OH–, NH4+, CH3NH2, H2O large number of coordination entities using the property of isomerism. The
Valence Bond Theory (VBT) explains the formation, magnetic behaviour and
 geometrical shapes of coordination compounds. It, however, fails to describe the 5. (a) (i) Write the electronic configuration of d5 on the basis of crystal field splitting
optical properties of these compounds. The Crystal Field Theory (CFT) explains theory if ∆ o < P.
the effect of different crystal fields (provided by the ligands taken as point (ii) [Fe(CN)6]3- is weakly paramagnetic whereas [Fe(CN)6]4- is
charges) on the degeneracy of d-orbital energies of the central metal atom/ion. diamagnetic. Give reason to support this statement. [Atomic no. : Fe = 26]
Answer the following questions : (iii) Write the number of ions produced from the complex[Co(NH3)6]Cl2 in solution.
(i) When a coordination compound NiCl2 . 6H2O is mixed with OR
AgNO3 solution, 2 moles of AgCl are precipitated per mole of (b) (i) Calculate the spin only magnetic moment of the complex
the compound. Write the structural formula of the complex [CoF6]3- . (Atomic no. of Co = 27)
and secondary valency for Nickel ion. (ii) Write the IUPAC name of the given complex: [CrCl2(H2O)4]Cl
(ii) Write the IUPAC name of the ionisation isomer of [Co(NH3)5(SO4)]Cl. (iii) Which out of the two complexes is more stable and why?
(iii) Using Valence Bond Theory, predict the geometry and [Fe(H2O)6]3+, [Fe(C2O4)3]3-
magnetic nature of : CBSE 2021
(1) [Ni(CO)4] (2) [Fe(CN)6]3 [Atomic number : Ni = 28, Fe = 26] 1. The oxidation number of Co in [Co(en)3]2(SO4)3 is:
OR (i) +2 (ii) +3 (iii) +4 (iv) +6
(iii) Give reasons: 2. Which of the following ligands form a ‘chelate’ complex with metal ion.
(1) Low spin tetrahedral complexes are not formed. 2−¿¿
(a) H2O(b) CN- (c) C 2 O 4 (d) Cl-
(2) [Co(NH3)6]3+ is an inner orbital complex whereas [Ni(NH3)6]2+ is an outer
3. The Coordination number of Cr in [CrCl2(ox)2]3-
orbital complex. [Atomic number : Co = 27, Ni = 28]
(a) 6 (b) 5 (c) 4 (d) 3
4. The formula of the coordinationcompound
Tetraamminechloridonitrito-N-cobalt(III)chloride is
CBSE 2022
(a) [Co(NH3)4Cl(ONO)]Cl2 (b) [Co(NH3)4Cl2(NO2)]Cl
1. (a) On the basis of crystal field theory write the electronic configuration for d 4 ion
(c) [Co(NH3)4Cl(NO2)]Cl (d) [Co(NH3)4(NO2)]Cl3
with a strong field ligand for which ∆0 < P
5. Write hybridization and magnetic behaviour of the following complex: (i)
(b) Using valence bond theory, predict the hybridization and magnetic behaviour
[CoF6]3– (ii) [Ni(CN)4]2-
of [Ni(CN)4]2- .
6. (a) Write IUPAC name of [Mn(H2O)6]SO4
(c) Write formula of the following complex using IUPAC norms:
(b) Why is [Fe(CN)6]4- diamagnetic wile[FeF6]3- is paramagnetic.
Dichlorido bis(ethane-1,2-diamine)cobalt(III)
CBSE 2020
2. When a coordination compound NiCl2.6H2O mixed with AgNO3, 2 moles of AgCl
1. One mole of CrCl3 . 6H2O compound reacts with excess AgNO3 solution to yield
are precipitated per mole of the compound. Write
two moles of AgCl (s). The structural formula of the compound is
(i) Structural formula of the complex.
(A) [Cr(H2O)5 Cl] Cl2 . H2O (B) [Cr(H2O)3 Cl3] . 3H2O
(ii) Secondary valency of ‘Ni’ in the complex.
(C) [Cr(H2O)4 Cl2] Cl . 2H2O (D) [Cr(H2O)6] Cl3
(iii) IUPAC name of the complex.
2. How many ions are produced from the complex [Co(NH3)5Cl] Cl2 in
3. (a) Write the hybridisation and magnetic character of the following
solution ?
complexes : (i) [NiCl4]2- (ii) [Co(NH3)6]3+ (iii) [FeF6]3-
[Atomic number : Ni = 28, Co = 27, Fe = 26] (a) 4 (b) 2 (c) 3 (d) 5
OR 3. The pair [Co(NH3)4 Cl2] Br2 and [Co(NH3)4 Br2] Cl2 will show
(b) (i) Write the IUPAC name of the following complex : [Co(NH3)4(H2O)Cl]Cl2 (a) Linkage isomerism (b) Hydrate isomerism
(ii) What is the difference between an Ambidentate and a Bidentate ligand? (c) Ionization isomerism (d) Coordinate isomerism
(iii) Out of [Fe(NH3)6]3+ and [Fe(C2O4)3]3- , which complex is more stable? 4. The oxidation state of Ni in [Ni(CO)4] is
4. (a) Using valence bond theory, predict the hybridization and magnetic behaviour of (a) 0 (b) 2 (c) 3 (d) 4
[CoF6]3- 5. Assertion (A): Linkage isomerism arises in coordination compounds
(b) Write IUPAC name of the complex: [CoBr2(en)2]+ because of ambidentate ligand.
(c) How many ions are produced from the complex [Co(NH3)6]Cl2 in solution? Reason (R): Ambidentate ligand like NO2 has two different donor atoms i.e., N and O.
6. Assertion (A): [Pt(en)2 Cl2]2+ complex is less stable than [Pt(NH3)4 Cl2]2+ complex. 4. (a) Although both [NiCl4]2– and [Ni(CO)4] have sp3 hybridisation yet
Reason (R): [Pt(en)2 Cl2]2+ complex shows chelate effect. [NiCl4]2– is paramagnetic and [Ni(CO)4] is diamagnetic. Give
7. Give the formulae of the following compounds reason. (Atomic no. of Ni = 28)
(a) Potassium tetrahydroxidozincate (II) (b) Hexaammineplatinum (IV) chloride (b) Write the electronic configuration of d5 on the basis of crystal field theory when
8. What type of isomerism is shown by the complex [Co(NH3)5 NO2] Cl2 (i) ∆o < P and (ii) ∆o > P
9. Assertion (A): Low spin tetrahedral complexes are rarely observed. 5. Write IUPAC name of the complex [Co(en)2(H2O)(CN)]2+.
Reason (R): The orbital splitting energies are not sufficiently large to OR
forcing pairing. Using IUPAC norms, write the formula of Ammonium tetrafluoridocobaltate(II).
6. (a) Give one chemical test as an evidence to show that
10. (a) Give the IUPAC name and electronic configuration of central metal atom in
[Co(NH3)5Cl]SO4 and [Co(NH3)5(SO4)]Cl are ionisation isomers.
terms of t2g and eg of K4[Mn(CN)6].
(b) [NiCl4]2– is paramagnetic while [Ni(CO)4] is diamagnetic though
(b) What is meant by ‘Chelate effect’? Give an example.
both are tetrahedral. Why? (Atomic no. of Ni = 28)
OR
Write the hybridisation and magnetic characters of the following (c) Write the electronic configuration of Fe(III) on the basis of crystal
complexes : (i) [Fe(CN)6]4– (ii) [CoF6]3– (iii) [Ni(CO)4] field theory when it forms an octahedral complex in the presence of (i) strong
[Atomic number: Fe = 26, Co = 27, Ni = 28] field ligand, and (ii) weak field ligand.
11. (a) Write the IUPAC name and hybridisation of the complex [CoF6]3–. (Atomic no. of Fe = 26)
(Given : Atomic number of Co = 27) 7. Write the hybridization and magnetic character of the following
(b) What type of isomerism is shown by the complex [Co(en)2 Cl2]2+ ? complexes :(i) [Fe(H2O)6]2+(ii) [Ni(CN)4]2-
Name the structure of an isomer of this complex which is optically active. [Atomic number : Fe = 26, Ni = 28]
12. Write the IUPAC names and hybridisation of the following complexes :(i) 8. What type of isomerism is shown by complex [Co(NH3)5Cl]SO4 ?
[Ni(CN)4]2– (ii) [Fe(H2O)6]2+ (Given: Atomic number Ni = 28, Fe = 26) OR
13. (a) Write the IUPAC name and hybridisation of the complex [Fe(CN)6]3–. Arrange the following in increasing order of crystal field splitting energy:
(Given: Atomic number of Fe = 26) [Cr(CN)6]3–, [Cr(NH3)6]3+, [CrCl6]3–
(b) What is the difference between an ambidentate ligand and a chelating ligand? 9. Using valence bond theory, predict the hybridization and magnetic
character of the following :
CBSE 2019 (a) [Co(NH3)6]3+ (b) [Ni(CO)4]
1. Write IUPAC name of the complex [Pt(en)2Cl2]. Draw structures of geometrical [At. no. : Co = 27, Ni = 28]
isomers for this complex. 10. Predict the number of unpaired electrons in the square planar [Pt(CN)4]2– ion.
OR OR
Using IUPAC norms write the formulae for the following: Amongst [Fe(C2O4)3]3– and [Fe(NH3)6]3+ which is more stable and why ?
(i) Hexaamminecobalt(III) sulphate
(ii) Potassium trioxalatochromate(III)
2. Out of [CoF6]3– and [Co(en)3]3+, which one complex is
(i) paramagnetic
(ii) more stable
(iii) inner orbital complex and
(iv) high spin complex
(Atomic no. of Co = 27)
3. Write IUPAC name of the complex [Co(en)2(NO2)Cl]+. What type of
structural isomerism is shown by this complex ?
OR
Using IUPAC norms, write the formulae for the following complexes:
(a) Hexaaquachromium(III) chloride
(b) Sodium trioxalatoferrate(III)