Coordination Compounds Class 12 Chemistry Exam Questions

Please refer to the below Coordination Compounds important questions for Class 12 Chemistry. These questions and answers have been prepared as per the latest NCERT Book for Class 12 Chemistry. Students should go through chapter wise Class 12 Chemistry Important Questions designed as per the latest examination pattern issued by CBSE.

Very Short Answer Questions :

Question. Write the IUPAC name of
[PtCl(NH₂CH₃)(NH₃)₂]Cl.
Answer : Diamminechlorido(methylamine)platinum(II) chloride.

Question. Write the IUPAC name of the complex [Cr(NH₃)₄Cl₂]Cl. 
Answer : IUPAC name of the complex [Cr(NH₃)₄Cl₂]Cl is tetraamminedichloridochromium (III) chloride.

Question. Using the IUPAC norms, write the systematic name of following :
[CoCl(NO₂)(NH₃)₄]Cl 
Answer : Tetraamminechloridonitrito-N-cobalt(III) chloride.

Question. Give IUPAC name of ionisation isomer of [Ni(NH₃)₃NO₃]Cl. 
Answer : Ionisation isomer of [(Ni(NH₃)₃NO₃]Cl is [Ni(NH₃)₃Cl]NO₃. The IUPAC name of this complex is triamminechloridonickel(II) nitrate.

Question. What is meant by chelate effect? 
Answer : When a di– or polydentate ligand uses its two or more donor atoms to bind a single metal ion. It is said to be a chelate ligand. Chelating ligands form more stable complexes than monodentate analogs. This is called chelating effect.

Question. Write the IUPAC name of [Co(NH₃)₅Cl]Cl₂.
(Atomic no. of Co = 27) 
Answer : Pentaamminechloridocobalt(III) chloride.

Question. When a coordination compound CoCl₃.6NH₃ is mixed with AgNO₃, 3 moles of AgCl are precipitated per mole of the compound. Write structural formula of the complex.
Answer : Structural formula : [Co(NH₃)₆]Cl₃

Question. Give an example of ionization isomerism.
Answer : [Co(NH₃)₅SO₄]Br and [Co(NH₃)₅ Br] SO₄

Question. Giving a suitable example, explain the following :
Ambidentate ligand 
Answer : Ambidentate ligand : A unidentate ligand which can coordinate to central metal atom through two different atoms is called ambidentate ligand. For example NO₂^– ion can coordinate either through nitrogen or through oxygen to the central metal atom/ion.

Question. Name the following coordination compound :
K₃[CrF₆] 
Answer : Potassium hexafluoridochromate(III). 

Question. What type of isomerism is exhibited by the following complex :
[Co(NH₃)₅SO₄]Cl 
Answer : Ionisation isomerism : [Co(NH₃)₅SO⁴]Cl and [CO(NH₃)₅Cl] SO₄

Question. Write the IUPAC name of [Pt(NH₃)₄Cl₂]Cl₂.
Answer : Tetraamminedichloridoplatinum (IV) chloride.

Question. Square planar complexes (of MX₂L₂ type) with coordination number of 4 exhibit geometrical isomerism whereas tetrahedral complexes with similar composition, do not. Why?
Answer : The tetrahedral complexes do not show geometrical isomerism because the relative positions of the atoms with respect to each other will be the same.

Question. What is a ligand? Give an example of a bidentate ligand. 
Answer : The ions or molecules bonded to the central atom in the coordination entity are called ligands. Ethylene diammine is a bidentate ligand. 

Question. What type of isomerism is exhibited by the complex [Co(NH₃)₅NO₂]²⁺? 
Answer : Linkage isomerism : [Co(NH₃)₅NO₂]²⁺ and [Co(ONO) (NH₃)₅]²⁺

Short Answer Questions :

Question. Write down the formula of :
Tetraamineaquachloridocobalt(III)chloride.
Answer : [Co(NH₃)₄(H₂O)(Cl)]Cl₂

Question. Give an example of coordination isomerism.
Answer : [Co(NH₃)₆][Cr(CN)₆] and [Cr (NH₃)₆][Co(CN)₆]

Question. When a co-ordination compound CrCl₃⋅6H₂O is mixed with AgNO₃, 2 moles of AgCl are precipitated per mole of the compound. Write structural formula of the complex.
Answer : For one mole of the compound, two moles of AgCl are precipitated which indicates that two ionisable chloride ions in the complex. Hence, its structural formula is [CrCl(H₂O)₅]Cl₂.H₂O 

Question. Write the IUPAC name of [Cr(NH₃)₆ [Co(CN)₆]. 
Answer : Hexaamminechromium(III) hexacyanocobaltate(III).

Question. When a co-ordination compound CrCl₃⋅6H₂O is mixed with AgNO₃, 2 moles of AgCl are precipitated per mole of the compound. Write IUPAC name of the complex. 
Answer : IUPAC name of the complex
[CrCl(H₂O)₅]Cl₂ ·H₂O is :
pentaaquachloridochromium (III) chloride. 

Question. Give an example of linkage isomerism.
Answer : [Co(NH₃)₅(NO₂)]Cl₂ and [Co(NH₃)₅(ONO)]Cl₂

Question. Using the IUPAC norms, write the systematic name of the following :
[Co(NH₃)₆] [Cr(CN)₆] 
Answer : Hexaamminecobalt(III)hexacyanochromate(III)

Question. What type of isomerism is shown by the following complex :
[Co(NH₃)₆][Cr(CN)₆] 
Answer : Coordination isomerism : Its coordination isomer [Cr(NH₃)₆][CO(CN)₆], in which NH3 ligands are bound to Cr³⁺ and CN ligands to Co³⁺.

Question. Using IUPAC norms write the formulae for the following coordination compounds :
(i) Hexaamminecobalt(III)chloride
(ii) Potassiumtetrachloridonickelate(II)
Answer : i) [Co(NH₃)₆]Cl₃
(ii) K₂[NiCl₄]

Question. Name the following coordination compounds according to IUPAC system of nomenclature :
(i) [Co(NH₃)₄(H₂O)Cl]Cl₂
(ii) [CrCl₂(en)₂]Cl, (en = ethane – 1,2-diamine)
Answer : (i) Tetraammineaquachloridocobalt(III) chloride
(ii) Dichloridobis(ethane-1,2-diamine)cobalt(III) chloride 

Question. What do you understand by ‘denticity of a ligand’? 
Answer : Denticity : The number of coordinating groups present in a ligand is called the denticity of ligand. For example, bidentate ligand ethane-1, 2-diamine has two donor nitrogen atoms which can link to central metal atom.
         H₂N^¨—CH₂—CH₂—N^¨H₂
          Ethane-1, 2-diamine 

Question. Explain the following terms giving a suitable example in each case :
(i) Ambident ligand
(ii) Denticity of a ligand 
Answer : (i) Ambidentate ligand : A unidentate ligand which can coordinate to central metal atom through two different atoms is called ambidentate ligand. For example NO₂^– ion can coordinate either through nitrogen or through oxygen to the central metal atom/ion.
(ii) Denticity : The number of coordinating groups present in a ligand is called the denticity of ligand. For example, bidentate ligand ethane-1, 2-diamine has two donor nitrogen atoms which can link to central metal atom.
         H₂N^¨—CH₂—CH₂—N^¨H₂
          Ethane-1, 2-diamine

Question. Write the IUPAC name of the following :
(i) [Co(NH₃)₆]Cl₃
(ii) [NiCl₄]^2–
(iii) K₃[Fe(CN)₆] 
Answer : (i) Hexaamminecobalt(III) chloride
(ii) Tetrachloridonickelate(II)ion
(iii) Potassiumhexacyanoferrate(III)

Question. Write the IUPAC name and draw the structure of each of the following complex entities :

Answer : (i) Trioxalatocobaltate (III)
(ii) Hexacarbonylchromium (0)
(iii) Trichloroetheneplatinum (III)

Question. (i) Write down the IUPAC name of the following complex :
[Cr(NH₃)₂Cl₂(en)]Cl (en = ethylenediamine)
(ii) Write the formula for the following complex :
Pentaamminenitrito-O-cobalt (III).
Answer : (i) Diamminedichlorido(ethane-1,2-diamine) chromium(III) chloride.
(ii) [Co(NH₃)₅(ONO)]²⁺

Question. (i) Write down the IUPAC name of the following complex. [Cr (en)₃]Cl₃
(ii) Write the formula for the following complex.
Potassium trioxalato chromate (III)
Answer : Tris(ethylenediammine)chromium(III) chloride
(ii) K₃[Cr(ox)₃]

Question. Write down the IUPAC name for each of the following complexes :
(i) [Co(NH₃)₅Cl]Cl₂
(ii) K3[Fe(CN)₆]
(iii) [NiCl₄]^2– 
Answer : (i) Pentaamminechloridocobalt(III)chloride
(ii) Potassiumhexacyanoferrate(III)
(iii) Tetrachloridonickelate(II)ion

Question. Name the following coordination entities and draw the structures of their stereoisomers :
(i) [Co(en)₂Cl₂]⁺ (en = ethane-1,2-diamine)
(ii) [Cr(C₂O₄)₃]^3–
(iii) [Co(NH₃)₃Cl₃]
(Atomic numbers Cr = 24, Co = 27) 
Answer : (i) [CoCl₂(en)₂]⁺ : Dichloridobis(ethane-1,2-diamine) cobalt(III) ion 
It will exist in two geometrical isomeric forms :

Question. Draw one of the geometrical isomers of the complex [Pt(en)₂Cl₂]²⁺ which is optically active.
Answer : cis-isomer of the complex [Pt(en)₂Cl₂]²⁺ is optically active

Question. Write the structures and names of all the stereoisomers of the following compounds :
(i) [Pt(NH₃)₂Cl₂]
(ii) [Fe(NH₃)₄Cl₂]Cl
Answer : (i) [Pt(NH₃)₂Cl₂] 

(ii) [Fe(NH₃)₄Cl₂]Cl

Question. Draw the geometrical isomers of complex [Pt(NH₃)₂Cl₂]. 
Answer : 

Question. Indicate the types of isomerism exhibited by the following complexes :
(i) [Co(NH₃)₅(NO₂)]²⁺
(ii) [Pt(NH₃)₂Cl₂]
Answer : (i) Linkage isomerism : [Co(NH₃)₅NO₂]²⁺ and [Co(ONO) (NH₃)₅]²⁺
(ii)

Question. Write down the IUPAC name of the complex [Pt(en)₂Cl₂]²⁺. What type of isomerism is shown by this complex?
Answer : IUPAC name – Dichloridobis(ethane-1,2-diamine) platinum(IV) ion. This complex shows geometrical and optical isomerism.