Coordination compounds play a vital role in modern chemistry, biology, and industry. In Class 12 Chemistry Coordination Compounds NCERT, students learn about complex ions formed when central metal atoms are bonded with molecules or ions called ligands.

Class 12 Chemistry Coordination Compounds NCERT Answers

This chapter covers essential concepts such as ligands, coordination number, isomerism, Werner’s theory, and the bonding nature of these compounds. Understanding coordination chemistry lays the foundation for advanced studies in bioinorganic chemistry, analytical techniques, and catalysis. The chapter also includes IUPAC naming, properties, and real-life applications of coordination compounds.

Class 12 Chemistry Coordination Compounds NCERT Textbook Answers

Question 1:

Explain the bonding in coordination compounds in terms of Werner’s postulates.

Answer:
Werner’s postulates:

  1. Metals show two types of valency – primary (ionisable) and secondary (non-ionisable).
  2. Primary valency corresponds to the oxidation state; secondary valency corresponds to the coordination number.
  3. Secondary valencies are satisfied by ligands forming coordinate bonds.
  4. Geometry of coordination compounds depends on the number and arrangement of ligands.

Question 2:

FeSO₄ solution mixed with KCN gives a complex [Fe(CN)₆]⁴⁻. Write the oxidation state, coordination number, and magnetic behaviour of the complex.

Answer:

  • Oxidation state of Fe: +2
  • CN⁻ is a strong field ligand → low spin complex
  • Electronic configuration of Fe²⁺ = 3d⁶ → all paired in low spin
  • Magnetic behaviour: Diamagnetic
  • Coordination number: 6 (hexadentate)

Question 3:

Explain with two examples each of the following: coordination entity, ligand, coordination number, coordination sphere, central atom/ion.

Answer:

  1. Coordination entity:
    • [Co(NH₃)₆]³⁺, [Fe(CN)₆]⁴⁻
  2. Ligand:
    • NH₃ (neutral), Cl⁻ (monodentate anion)
  3. Coordination number:
    • Number of ligands directly attached; e.g., 6 in [Co(NH₃)₆]³⁺
  4. Coordination sphere:
    • Part inside square brackets in a complex; e.g., [CoCl₆]³⁻
  5. Central atom/ion:
    • Metal ion to which ligands are bonded; e.g., Co³⁺ in [Co(NH₃)₆]³⁺

Question 4:

What is meant by unidentate, bidentate, and ambidentate ligands? Give examples.

Answer:

  • Unidentate: Donates one lone pair (e.g., NH₃, Cl⁻)
  • Bidentate: Donates two lone pairs from two atoms (e.g., ethylenediamine – en)
  • Ambidentate: Can coordinate through two different atoms but only one at a time (e.g., NO₂⁻ via N or O)

Question 5:

Specify the oxidation number of the central atom in the following complexes:
(i) [Co(H₂O)(CN)₅]²⁻
(ii) [PtCl₄]²⁻
(iii) K₃[Fe(CN)₆]
(iv) [Cr(NH₃)₃Cl₃]
(v) [Fe(H₂O)₆]³⁺
(vi) [Co(en)₃]³⁺

Answer:
(i) Co = +3
(ii) Pt = +2
(iii) Fe = +3
(iv) Cr = +3
(v) Fe = +3
(vi) Co = +3

Question 6:

Draw structures of: [Co(NH₃)₆]³⁺, [Cr(H₂O)₆]³⁺, [Fe(CN)₆]³⁻, [Co(en)₃]³⁺

Answer:
These are all octahedral complexes with coordination number 6.
Each ligand occupies one position around the central metal ion.

Question 7:

What will be the coordination number of each central atom in the following: (i) [PtCl₆]²⁻, (ii) [Ni(CO)₄]

Answer:
(i) [PtCl₆]²⁻ → Coordination number = 6 (6 Cl⁻ ligands)
(ii) [Ni(CO)₄] → Coordination number = 4 (4 CO ligands)

Question 8:

List the names of monodentate ligands.

Answer:

  • NH₃ (ammine)
  • Cl⁻ (chloro)
  • H₂O (aqua)
  • CN⁻ (cyano)
  • NO₂⁻ (nitro or nitrito)

Question 9:

Define: (i) Coordination number (ii) Coordination entity (iii) Ligand

Answer:
(i) Coordination number: Number of ligand donor atoms attached to central metal ion.
(ii) Coordination entity: Central atom/ion with attached ligands.
(iii) Ligand: Ion or molecule that donates a pair of electrons to metal ion.

Question 10:

What is the difference between a double salt and a coordination compound?

Answer:

  • Double salt dissociates completely in water to give all ions.
    e.g., Mohr’s salt → Fe²⁺, NH₄⁺, SO₄²⁻
  • Coordination compound retains its identity in solution.
    e.g., [Cu(NH₃)₄]²⁺ remains as a complex ion in water.

Question 11:

Write IUPAC names of the following:
(i) [Co(NH₃)₆]Cl₃
(ii) [Pt(NH₃)₂Cl₂]
(iii) [Cr(en)₃]³⁺
(iv) K₃[Fe(CN)₆]
(v) [Ni(CO)₄]

Answer:
(i) Hexaamminecobalt(III) chloride
(ii) Diamminedichloroplatinum(II)
(iii) Tris(ethylenediamine)chromium(III) ion
(iv) Potassium hexacyanoferrate(III)
(v) Tetracarbonylnickel(0)

Question 12:

Explain: Geometrical and optical isomerism in coordination compounds.

Answer:

  • Geometrical isomerism: Different spatial arrangements (e.g., cis/trans in square planar or octahedral).
  • Optical isomerism: Non-superimposable mirror images (chiral complexes) show optical isomerism.

Question 13:

Which is more stable: [Fe(CN)₆]³⁻ or [Fe(H₂O)₆]³⁺? Why?

Answer:
[Fe(CN)₆]³⁻ is more stable due to:

  • CN⁻ being a strong field ligand
  • Forms low-spin, more stable complex
  • Water is a weak field ligand → less stable complex
You can access the official NCERT Solutions for Class 10 Mathematics on the NCERT website at the following link:

NCERT Class 10 Mathematics Solutions

📘 Math & Science Solutions by Class

🔹 Class 10

🔹 Class 9

🔹 Class 8

🔹 Class 7

🔹 Class 6

🔹 Class 12

🔹 Class 11

Learn more about circle formulas from NCERT.

Class-wise Solutions

Class 12:

Class 12 Physics – NCERT Solutions

Class 12 Chemistry – NCERT Solutions

Class 11:

Class 10:

Class 9:

Class 8:

Class 7:

Class 6:

Subject-wise Solutions

Physics:

Chemistry:

Biology:

Math:

Science:

NEET BIOLOGY

Class 12 Chemistry Coordination Compounds NCERT Answers provide a detailed and conceptual understanding of complex compounds, ligands, and coordination numbers. By going through these solutions, students can strengthen their grasp on important topics like Werner’s theory, IUPAC naming, and isomerism in coordination compounds. These Class 12 Chemistry Coordination Compounds NCERT Answers are prepared as per the CBSE curriculum to help students perform well in exams.

Whether you’re revising or preparing for competitive exams, Class 12 Chemistry Coordination Compounds NCERT Answers serve as a reliable and accurate resource. Make sure to practice thoroughly with Class 12 Chemistry Coordination Compounds NCERT Answers to build confidence and score high in your board exams.