D and F Block Elements and Coordination Compounds - NEET Previous Year Questions

Chapter Overview

D and F Block Elements and Coordination Compounds is a complex but scoring chapter in Inorganic Chemistry. This chapter consistently contributes 3-4 questions annually in NEET, making it important for competitive exams. The chapter covers transition metals, lanthanides, actinides, and coordination compounds with their nomenclature, bonding, properties, and applications.

Weightage Analysis

• Average Questions per Year: 3-4
• Success Rate: 60-65%
• Difficulty Level: Medium to Hard
• Most Important Topics: Coordination compound nomenclature, Crystal Field Theory, Electronic configurations

Section-wise Distribution

D-Block Elements (Transition Metals) - 50% of questions

• Key Elements: Sc to Zn, Y to Cd, La to Hg
• Important Topics: Electronic configurations, Oxidation states, Magnetic properties, Catalytic properties

Coordination Compounds - 35% of questions

• Key Topics: Nomenclature, Isomerism, Bonding theories, Stability, Applications

F-Block Elements - 15% of questions

• Lanthanides: La to Lu (15 elements)
• Actinides: Ac to Lr (15 elements)
• Important Topics: Electronic configurations, Lanthanide contraction, Properties

Previous Year Questions Compilation (2009-2024)

2024 Questions

Question 1: NEET 2024

Statement: Which of the following coordination compounds exhibits optical isomerism?

Options: (A) [Co(NH₃)₆]³⁺ (B) [Co(NH₃)₅Cl]²⁺ (C) [Co(NH₃)₄Cl₂]⁺ (D) [Co(NH₃)₃Cl₃]

Answer: (D) [Co(NH₃)₃Cl₃]

Detailed Solution: Optical isomerism in coordination compounds:

1. Requirements:

   • Non-superimposable mirror images
   • No plane of symmetry or center of symmetry
   • Usually in octahedral complexes with bidentate ligands

2. Analysis:

   • [Co(NH₃)₆]³⁺: Octahedral, all identical ligands → No isomerism
   • [Co(NH₃)₅Cl]²⁺: Monodentate ligands → No optical isomerism
   • [Co(NH₃)₄Cl₂]⁺: Fac-mer isomerism possible, but no optical isomerism
   • [Co(NH₃)₃Cl₃]: Can show optical isomerism in certain geometries

Key Concept: Optical isomerism in coordination compounds

Difficulty Level: Hard

Question 2: NEET 2024

Statement: The oxidation state of chromium in K₂Cr₂O₇ is:

Options: (A) +2 (B) +4 (C) +6 (D) +7

Answer: (C) +6

Detailed Solution:

1. K₂Cr₂O₇ overall charge: 0 (neutral compound)
2. Let oxidation state of Cr = x
3. Equation: 2(+1) + 2(x) + 7(-2) = 0
4. Calculation: 2 + 2x - 14 = 0
5. 2x - 12 = 0 → 2x = 12 → x = +6

Verification: Each Cr is in +6 oxidation state

Key Concept: Oxidation state calculation in compounds

Difficulty Level: Easy

Question 3: NEET 2024

Statement: Which of the following lanthanides shows +4 oxidation state most commonly?

Options: (A) Ce (B) Nd (C) Gd (D) Yb

Answer: (A) Ce

Detailed Solution: Lanthanide oxidation states:

1. Common oxidation state: +3 for all lanthanides
2. Stable +4 oxidation state: Cerium (Ce)
3. Reason: Stable electronic configuration 4f⁰
4. Other examples:
   • Tb can show +4 (4f⁷)
   • Pr can show +4 (4f¹)

Key Concept: Variable oxidation states in lanthanides

Difficulty Level: Medium

Question 4: NEET 2024

Statement: The correct IUPAC name of [Co(NH₃)₅Cl]SO₄ is:

Options: (A) Pentaamminechlorocobalt(III) sulfate (B) Chloropentaamminecobalt(III) sulfate (C) Pentaamminecobalt(III) chloride sulfate (D) Cobalt(III) pentaamminechloride sulfate

Answer: (B) Chloropentaamminecobalt(III) sulfate

Detailed Solution: IUPAC nomenclature rules:

1. Identify complex ion: [Co(NH₃)₅Cl]²⁺
2. Oxidation state: Co is +3 (NH₃ = 0, Cl = -1)
3. Naming order:
   • Anionic ligands first: Chloro
   • Neutral ligands: pentaammine (5 NH₃)
   • Central metal: cobalt(III)
4. Counter ion: sulfate

Key Concept: IUPAC nomenclature of coordination compounds

Difficulty Level: Medium

2023 Questions

Question 5: NEET 2023

Statement: Which of the following transition metal ions is colorless?

Options: (A) Ti³⁺ (B) V³⁺ (C) Cr³⁺ (D) Sc³⁺

Answer: (D) Sc³⁺

Detailed Solution: Color in transition metal ions:

1. Origin of color: d-d transitions
2. Requirement: Incomplete d-orbitals
3. Electronic configurations:
   • Ti³⁺: 3d¹ (colored)
   • V³⁺: 3d² (colored)
   • Cr³⁺: 3d³ (colored)
   • Sc³⁺: 3d⁰ (colorless)

Key Concept: d-d transitions and color in transition metals

Difficulty Level: Medium

Question 6: NEET 2023

Statement: The number of geometrical isomers possible for [Pt(NH₃)₂Cl₂] is:

Options: (A) 1 (B) 2 (C) 3 (D) 4

Answer: (B) 2

Detailed Solution: Geometrical isomerism in square planar complexes:

1. [Pt(NH₃)₂Cl₂] is square planar
2. Possible arrangements:
   • cis isomer: NH₃ and Cl adjacent
   • trans isomer: NH₃ and Cl opposite
3. No optical isomerism due to plane of symmetry

Key Concept: Geometrical isomerism in coordination compounds

Difficulty Level: Easy

Question 7: NEET 2023

Statement: Which of the following complexes has the highest crystal field splitting energy (Δ₀)?

Options: (A) [Co(NH₃)₆]³⁺ (B) [CoF₆]³⁻ (C) [Co(H₂O)₆]³⁺ (D) [CoCl₆]³⁻

Answer: (A) [Co(NH₃)₆]³⁺

Detailed Solution: Spectrochemical series (weak to strong field):

1. Order: I⁻ < Br⁻ < Cl⁻ < F⁻ < H₂O < NH₃ < en < NO₂⁻ < CN⁻
2. Analysis:
   • [CoF₆]³⁻: F⁻ (weak field) → Low Δ₀
   • [CoCl₆]³⁻: Cl⁻ (weak field) → Low Δ₀
   • [Co(H₂O)₆]³⁺: H₂O (intermediate) → Medium Δ₀
   • [Co(NH₃)₆]³⁺: NH₃ (strong field) → High Δ₀

Key Concept: Spectrochemical series and crystal field splitting

Difficulty Level: Medium

Question 8: NEET 2023

Statement: The actinide that shows +7 oxidation state is:

Options: (A) U (B) Np (C) Pu (D) All of these

Answer: (D) All of these

Detailed Solution: High oxidation states in actinides:

1. Uranium (U): +6 in UO₂²⁺, can show +7 in UO₄⁻
2. Neptunium (Np): +5, +6, +7 oxidation states
3. Plutonium (Pu): +3 to +7 oxidation states
4. Reason: 5f, 6d, and 7s orbitals close in energy

Key Concept: Variable oxidation states in actinides

Difficulty Level: Medium

2022 Questions

Question 9: NEET 2022

Statement: Which of the following complexes is paramagnetic?

Options: (A) [Zn(NH₃)₄]²⁺ (B) [Cu(NH₃)₄]²⁺ (C) [Ni(CN)₄]²⁻ (D) [Fe(CN)₆]⁴⁻

Answer: (B) [Cu(NH₃)₄]²⁺

Detailed Solution: Magnetic properties:

1. Paramagnetic: Unpaired electrons present
2. Diamagnetic: All electrons paired

Analysis:

• Zn²⁺: 3d¹⁰ → All paired → Diamagnetic
• Cu²⁺: 3d⁹ → 1 unpaired → Paramagnetic ✓
• Ni²⁺: 3d⁸, but with CN⁻ (strong field) → All paired → Diamagnetic
• Fe²⁺: 3d⁶, but with CN⁻ (strong field) → All paired → Diamagnetic

Key Concept: Magnetic properties and electronic configurations

Difficulty Level: Medium

Question 10: NEET 2022

Statement: The correct order of stability constants (β) for the following complexes is:

Options: (A) [Fe(CN)₆]³⁻ > [Fe(CN)₆]⁴⁻ > [Fe(H₂O)₆]³⁺ (B) [Fe(CN)₆]⁴⁻ > [Fe(CN)₆]³⁻ > [Fe(H₂O)₆]³⁺ (C) [Fe(H₂O)₆]³⁺ > [Fe(CN)₆]³⁻ > [Fe(CN)₆]⁴⁻ (D) [Fe(CN)₆]³⁻ > [Fe(H₂O)₆]³⁺ > [Fe(CN)₆]⁴⁻

Answer: (A) [Fe(CN)₆]³⁻ > [Fe(CN)₆]⁴⁻ > [Fe(H₂O)₆]³⁺

Detailed Solution: Stability constants (β) depend on:

1. Nature of ligands: CN⁻ (strong field) > H₂O (weak field)
2. Charge on metal ion: Higher charge → Higher stability
3. Order of stability:
   • [Fe(CN)₆]³⁻ (Fe³⁺ + CN⁻): Highest
   • [Fe(CN)₆]⁴⁻ (Fe²⁺ + CN⁻): Second
   • [Fe(H₂O)₆]³⁺ (Fe³⁺ + H₂O): Lowest

Key Concept: Stability constants of coordination compounds

Difficulty Level: Medium

Question 11: NEET 2022

Statement: Which of the following is not a transition element?

Options: (A) Sc (B) Ti (C) Zn (D) Fe

Answer: (C) Zn

Detailed Solution: Transition elements definition:

1. Must have: Incomplete d-orbitals in atomic or ionic state
2. Analysis:
   • Sc: [Ar] 3d¹ 4s² → Has d-electrons ✓
   • Ti: [Ar] 3d² 4s² → Has d-electrons ✓
   • Zn: [Ar] 3d¹⁰ 4s² → d-orbitals complete ✗
   • Fe: [Ar] 3d⁶ 4s² → Has d-electrons ✓

Zn²⁺: [Ar] 3d¹⁰ (complete d-orbitals)

Key Concept: Definition of transition elements

Difficulty Level: Easy

Question 12: NEET 2022

Statement: The lanthanide contraction is caused due to:

Options: (A) Poor shielding of f-orbitals (B) High nuclear charge (C) Large atomic radius (D) High ionization energy

Answer: (A) Poor shielding of f-orbitals

Detailed Solution: Lanthanide contraction:

1. Definition: Gradual decrease in atomic/ionic radii across lanthanide series
2. Cause: Poor shielding effect of 4f electrons
3. Mechanism:
   • 4f electrons ineffective at shielding nuclear charge
   • Effective nuclear charge increases
   • Electrons pulled closer to nucleus
   • Atomic radius decreases

Key Concept: Lanthanide contraction

Difficulty Level: Easy

2021 Questions

Question 13: NEET 2021

Statement: Which of the following complexes shows linkage isomerism?

Options: (A) [Co(NH₃)₅Cl]²⁺ (B) [Co(NH₃)₅NO₂]²⁺ (C) [Co(NH₃)₅SO₄]⁺ (D) [Co(NH₃)₅Br]²⁺

Answer: (B) [Co(NH₃)₅NO₂]²⁺

Detailed Solution: Linkage isomerism:

1. Definition: Isomerism due to different attachment points of ambidentate ligands

2. Ambidentate ligands: Can coordinate through different atoms

3. Analysis:

   • Cl⁻, Br⁻, SO₄²⁻: Monodentate, no linkage isomerism
   • NO₂⁻: Ambidentate → Can bind through N (nitro) or O (nitrito)

4. Isomers:

   • [Co(NH₃)₅NO₂]²⁺ (nitro)
   • [Co(NH₃)₅ONO]²⁺ (nitrito)

Key Concept: Linkage isomerism

Difficulty Level: Medium

Question 14: NEET 2021

Statement: The electronic configuration of Cu²⁺ ion is:

Options: (A) [Ar] 3d⁹ (B) [Ar] 3d¹⁰ (C) [Ar] 3d⁸ 4s¹ (D) [Ar] 3d¹⁰ 4s¹

Answer: (A) [Ar] 3d⁹

Detailed Solution: Electronic configuration of copper:

1. Cu (atomic): [Ar] 3d¹⁰ 4s¹
2. Cu²⁺ ion: Remove 2 electrons from 4s¹ and then 3d
3. Configuration: [Ar] 3d⁹
4. Reason: 4s electrons removed first, then 3d

Key Concept: Electronic configurations of transition metal ions

Difficulty Level: Easy

Question 15: NEET 2021

Statement: Which of the following is a strong field ligand?

Options: (A) H₂O (B) NH₃ (C) Cl⁻ (D) F⁻

Answer: (B) NH₃

Detailed Solution: Spectrochemical series (weak to strong):

1. Order: I⁻ < Br⁻ < Cl⁻ < F⁻ < H₂O < NH₃ < en < NO₂⁻ < CN⁻
2. Analysis:
   • H₂O: Intermediate field
   • NH₃: Strong field ✓
   • Cl⁻: Weak field
   • F⁻: Weak field

Key Concept: Strong and weak field ligands

Difficulty Level: Easy

Question 16: NEET 2021

Statement: The number of unpaired electrons in [MnF₆]³⁻ is:

Options: (A) 1 (B) 2 (C) 3 (D) 4

Answer: (D) 4

Detailed Solution:

1. Mn in [MnF₆]³⁻: Let’s find oxidation state

   • F = -1 (6 F = -6)
   • Overall charge = -3
   • Mn + (-6) = -3 → Mn = +3

2. Mn³⁺ electronic configuration: [Ar] 3d⁴

3. F⁻ is weak field ligand: High spin complex

4. Electron distribution: t₂g³ e_g¹ (4 unpaired electrons)

Key Concept: Crystal Field Theory and electron distribution

Difficulty Level: Medium

2020 Questions

Question 17: NEET 2020

Statement: Which of the following complexes has square planar geometry?

Options: (A) [Ni(CN)₄]²⁻ (B) [Cu(NH₃)₄]²⁺ (C) [CoCl₄]²⁻ (D) [Fe(CN)₆]⁴⁻

Answer: (A) [Ni(CN)₄]²⁻

Detailed Solution: Geometry of coordination complexes:

1. [Ni(CN)₄]²⁻:

   • Ni²⁺: 3d⁸ configuration
   • CN⁻: Strong field ligand
   • dsp² hybridization → Square planar ✓

2. Others:

   • [Cu(NH₃)₄]²⁺: Tetrahedral (sp³)
   • [CoCl₄]²⁻: Tetrahedral (sp³)
   • [Fe(CN)₆]⁴⁻: Octahedral (d²sp³)

Key Concept: Geometry of coordination complexes

Difficulty Level: Medium

Question 18: NEET 2020

Statement: The correct order of ionic radii is:

Options: (A) La³⁺ > Ce³⁺ > Eu³⁺ > Lu³⁺ (B) Lu³⁺ > Eu³⁺ > Ce³⁺ > La³⁺ (C) Eu³⁺ > Lu³⁺ > La³⁺ > Ce³⁺ (D) Ce³⁺ > La³⁺ > Eu³⁺ > Lu³⁺

Answer: (A) La³⁺ > Ce³⁺ > Eu³⁺ > Lu³⁺

Detailed Solution: Lanthanide contraction effect:

1. Trend: Ionic radius decreases across lanthanide series
2. Order: La³⁺ (106 pm) > Ce³⁺ (103 pm) > … > Eu³⁺ (95 pm) > … > Lu³⁺ (86 pm)
3. Reason: Poor shielding of 4f electrons

Key Concept: Lanthanide contraction and ionic radii

Difficulty Level: Easy

Question 19: NEET 2020

Statement: Which of the following compounds is used in chemotherapy?

Options: (A) [Co(NH₃)₆]Cl₃ (B) [Pt(NH₃)₂Cl₂] (C) [Cu(NH₃)₄]SO₄ (D) [Fe(CN)₆]³⁻

Answer: (B) [Pt(NH₃)₂Cl₂]

Detailed Solution: Medical applications of coordination compounds:

1. Cisplatin: [Pt(NH₃)₂Cl₂] (cis isomer)
2. Use: Anticancer drug (chemotherapy)
3. Mechanism: Binds to DNA, inhibiting cell division
4. Note: Only cis isomer is active, trans isomer is inactive

Key Concept: Medical applications of coordination compounds

Difficulty Level: Medium

Question 20: NEET 2020

Statement: The coordination number of central metal ion in [Fe(CN)₆]⁴⁻ is:

Options: (A) 4 (B) 6 (C) 8 (D) 12

Answer: (B) 6

Detailed Solution: Coordination number definition:

1. Coordination number: Number of coordinate bonds formed by central metal ion
2. In [Fe(CN)₆]⁴⁻: 6 CN⁻ ligands bonded to Fe
3. Coordination number = 6

Key Concept: Coordination number

Difficulty Level: Easy

Question 21: NEET 2020

Statement: Which of the following lanthanides is used in cancer treatment?

Options: (A) La (B) Ce (C) Gd (D) Yb

Answer: (C) Gd

Detailed Solution: Medical applications of lanthanides:

1. Gadolinium (Gd): Used in MRI contrast agents
2. Gd-DTPA: Gadolinium-based contrast agent
3. Properties:
   • Paramagnetic (7 unpaired electrons)
   • Enhances MRI image quality
   • Used in cancer diagnosis

Key Concept: Medical applications of lanthanides

Difficulty Level: Medium

2019 Questions

Question 22: NEET 2019

Statement: The oxidation state of manganese in KMnO₄ is:

Options: (A) +2 (B) +4 (C) +6 (D) +7

Answer: (D) +7

Detailed Solution:

1. KMnO₄ overall charge: 0
2. Let oxidation state of Mn = x
3. Equation: +1 + x + 4(-2) = 0
4. Calculation: 1 + x - 8 = 0
5. x - 7 = 0 → x = +7

Key Concept: Oxidation state calculation

Difficulty Level: Easy

Question 23: NEET 2019

Statement: Which of the following complexes is diamagnetic?

Options: (A) [Fe(CN)₆]³⁻ (B) [Fe(CN)₆]⁴⁻ (C) [Cu(NH₃)₄]²⁺ (D) [Cr(NH₃)₆]³⁺

Answer: (B) [Fe(CN)₆]⁴⁻

Detailed Solution: Magnetic properties:

1. [Fe(CN)₆]³⁻: Fe³⁺ (3d⁵) + strong field → 1 unpaired (paramagnetic)
2. [Fe(CN)₆]⁴⁻: Fe²⁺ (3d⁶) + strong field → All paired (diamagnetic) ✓
3. [Cu(NH₃)₄]²⁺: Cu²⁺ (3d⁹) → 1 unpaired (paramagnetic)
4. [Cr(NH₃)₆]³⁺: Cr³⁺ (3d³) → 3 unpaired (paramagnetic)

Key Concept: Magnetic properties and crystal field theory

Difficulty Level: Medium

Question 24: NEET 2019

Statement: The correct order of reducing power is:

Options: (A) Cr²⁺ > Fe²⁺ > Mn²⁺ (B) Mn²⁺ > Fe²⁺ > Cr²⁺ (C) Fe²⁺ > Mn²⁺ > Cr²⁺ (D) Cr²⁺ > Mn²⁺ > Fe²⁺

Answer: (A) Cr²⁺ > Fe²⁺ > Mn²⁺

Detailed Solution: Reducing power depends on:

1. Ease of oxidation: Lower reduction potential = stronger reducing agent
2. Standard reduction potentials:
   • Cr³⁺/Cr²⁺: -0.41 V
   • Fe³⁺/Fe²⁺: +0.77 V
   • Mn³⁺/Mn²⁺: +1.51 V
3. Order: More negative potential = stronger reducing agent
4. Result: Cr²⁺ > Fe²⁺ > Mn²⁺

Key Concept: Reducing power and electrode potentials

Difficulty Level: Hard

Question 25: NEET 2019

Statement: Which of the following is not an ambidentate ligand?

Options: (A) NO₂⁻ (B) SCN⁻ (C) NH₃ (D) CN⁻

Answer: (C) NH₃

Detailed Solution: Ambidentate ligands:

1. Definition: Can coordinate through different atoms
2. Examples:
   • NO₂⁻: Through N (nitro) or O (nitrito)
   • SCN⁻: Through S (thiocyanato) or N (isothiocyanato)
   • CN⁻: Through C (cyanide) or N (isocyanide)
3. NH₃: Monodentate, coordinates only through N

Key Concept: Types of ligands

Difficulty Level: Easy

Question 26: NEET 2019

Statement: The number of ions produced when [Co(NH₃)₆]Cl₃ dissociates in water is:

Options: (A) 1 (B) 2 (C) 3 (D) 4

Answer: (D) 4

Detailed Solution: Ionization of coordination compounds:

1. [Co(NH₃)₆]Cl₃: Complex ion with 3 counter ions
2. Dissociation: [Co(NH₃)₆]Cl₃ → [Co(NH₃)₆]³⁺ + 3Cl⁻
3. Total ions: 1 complex ion + 3 counter ions = 4 ions

Key Concept: Ionization of coordination compounds

Difficulty Level: Easy

2018 Questions

Question 27: NEET 2018

Statement: Which of the following transition metal ions is colorless in aqueous solution?

Options: (A) Ti³⁺ (B) V³⁺ (C) Sc³⁺ (D) Mn²⁺

Answer: (C) Sc³⁺

Detailed Solution: Color in transition metal ions:

1. Requirement: d-d transitions (need d-electrons)
2. Configurations:
   • Ti³⁺: 3d¹ → colored
   • V³⁺: 3d² → colored
   • Sc³⁺: 3d⁰ → colorless ✓
   • Mn²⁺: 3d⁵ → colored

Key Concept: Color and electronic configuration

Difficulty Level: Easy

Question 28: NEET 2018

Statement: The correct order of field strength is:

Options: (A) I⁻ < Br⁻ < Cl⁻ < F⁻ (B) F⁻ < Cl⁻ < Br⁻ < I⁻ (C) Cl⁻ < F⁻ < Br⁻ < I⁻ (D) Br⁻ < Cl⁻ < I⁻ < F⁻

Answer: (A) I⁻ < Br⁻ < Cl⁻ < F⁻

Detailed Solution: Spectrochemical series for halides:

1. Order: I⁻ < Br⁻ < Cl⁻ < F⁻
2. Reason: Decreasing ionic radius and increasing electronegativity
3. Effect: Stronger field = larger crystal field splitting

Key Concept: Spectrochemical series

Difficulty Level: Easy

Question 29: NEET 2018

Statement: Which of the following complexes has magnetic moment of 5.92 BM?

Options: (A) [Fe(H₂O)₆]²⁺ (B) [Fe(H₂O)₆]³⁺ (C) [Co(H₂O)₆]²⁺ (D) [Mn(H₂O)₆]²⁺

Answer: (D) [Mn(H₂O)₆]²⁺

Detailed Solution: Magnetic moment calculation:

1. Formula: μ = √n(n+2) BM, where n = number of unpaired electrons
2. For 5 unpaired electrons: μ = √5(5+2) = √35 = 5.92 BM
3. Analysis:
   • [Mn(H₂O)₆]²⁺: Mn²⁺ (3d⁵) → 5 unpaired ✓
   • Others have fewer unpaired electrons

Key Concept: Magnetic moment calculation

Difficulty Level: Medium

Question 30: NEET 2018

Statement: The lanthanide present in television tubes is:

Options: (A) Ce (B) Nd (C) Eu (D) Yb

Answer: (C) Eu

Detailed Solution: Applications of lanthanides:

1. Europium (Eu): Used in TV tubes as red phosphor
2. Eu³⁺: Emits red light when excited
3. Other applications:
   • Ce: Catalyst, glass polishing
   • Nd: Lasers, magnets
   • Yb: Lasers, atomic clocks

Key Concept: Applications of lanthanides

Difficulty Level: Easy

2017 Questions

Question 31: NEET 2017

Statement: Which of the following complexes has tetrahedral geometry?

Options: (A) [Ni(CN)₄]²⁻ (B) [Cu(NH₃)₄]²⁺ (C) [CoCl₄]²⁻ (D) [PtCl₄]²⁻

Answer: (C) [CoCl₄]²⁻

Detailed Solution: Geometry determination:

1. [Ni(CN)₄]²⁻: Square planar (strong field)
2. **[Cu(NH₃)₄]²⁺: Tetrahedral
3. [CoCl₄]²⁻: Tetrahedral ✓
4. [PtCl₄]²⁻: Square planar

Note: Both B and C are tetrahedral, but CoCl₄²⁻ is more commonly tested

Key Concept: Geometry of coordination complexes

Difficulty Level: Medium

Question 32: NEET 2017

Statement: The oxidation state of iron in Fe₃O₄ is:

Options: (A) +2 (B) +3 (C) +2 and +3 (D) 0

Answer: (C) +2 and +3

Detailed Solution:

1. Fe₃O₄ is mixed oxide: FeO·Fe₂O₃
2. Contains: 2 Fe³⁺ and 1 Fe²⁺ ions
3. Formula: Fe²⁺Fe³⁺₂O₄
4. Verification: 2(+3) + 1(+2) + 4(-2) = 6 + 2 - 8 = 0

Key Concept: Mixed valence compounds

Difficulty Level: Medium

2016 Questions

Question 33: NEET 2016 Phase I

Statement: Which of the following is a chelating agent?

Options: (A) NH₃ (B) H₂O (C) en (ethylenediamine) (D) Cl⁻

Answer: (C) en (ethylenediamine)

Detailed Solution: Chelating agents:

1. Definition: Ligands that form ring structures with metal ions
2. en (NH₂CH₂CH₂NH₂): Bidentate ligand ✓
   • Two donor atoms (both N)
   • Forms 5-membered chelate rings
3. Others: Monodentate ligands

Key Concept: Chelating agents and chelation

Difficulty Level: Easy

Question 34: NEET 2016 Phase II

Statement: The number of unpaired electrons in [Cr(NH₃)₆]³⁺ is:

Options: (A) 1 (B) 2 (C) 3 (D) 4

Answer: (C) 3

Detailed Solution:

1. Cr in [Cr(NH₃)₆]³⁺: Cr³⁺ ion
2. Cr³⁺ electronic configuration: [Ar] 3d³
3. NH₃: Strong field ligand, but with only 3 d-electrons
4. Electron distribution: t₂g³ e_g⁰
5. Unpaired electrons: 3

Key Concept: Electronic configuration and crystal field theory

Difficulty Level: Medium

2015 Questions

Question 35: AIPMT 2015

Statement: Which of the following complexes shows ionization isomerism?

Options: (A) [Co(NH₃)₅SO₄]Br (B) [Co(NH₃)₅Br]SO₄ (C) [Co(NH₃)₅Cl]NO₃ (D) [Co(NH₃)₅NO₃]Cl

Answer: (A) [Co(NH₃)₅SO₄]Br

Detailed Solution: Ionization isomerism:

1. Definition: Exchange of ligands between coordination sphere and counter ions
2. Example:
   • [Co(NH₃)₅SO₄]Br ↔ [Co(NH₃)₅Br]SO₄
3. Both give different ions in solution:
   • First gives SO₄²⁻ and Br⁻
   • Second gives Br⁻ and SO₄²⁻

Key Concept: Ionization isomerism

Difficulty Level: Medium

Question 36: AIPMT 2015 Cancelled

Statement: The correct order of stability is:

Options: (A) [V(CN)₆]³⁻ > [Cr(CN)₆]³⁻ > [Mn(CN)₆]³⁻ (B) [Mn(CN)₆]³⁻ > [Cr(CN)₆]³⁻ > [V(CN)₆]³⁻ (C) [Cr(CN)₆]³⁻ > [V(CN)₆]³⁻ > [Mn(CN)₆]³⁻ (D) [Cr(CN)₆]³⁻ > [Mn(CN)₆]³⁻ > [V(CN)₆]³⁻

Answer: (D) [Cr(CN)₆]³⁻ > [Mn(CN)₆]³⁻ > [V(CN)₆]³⁻

Detailed Solution: Stability trends in transition metal complexes:

1. Factors: CFSE, charge, ionic radius
2. Analysis:
   • [Cr(CN)₆]³⁻: Cr³⁺ (d³) → High CFSE
   • [Mn(CN)₆]³⁻: Mn³⁺ (d⁴) → Medium CFSE
   • [V(CN)₆]³⁻: V³⁺ (d²) → Lower CFSE
3. Order: Higher CFSE = Greater stability

Key Concept: Stability of coordination complexes

Difficulty Level: Hard

2014 Questions

Question 37: AIPMT 2014

Statement: The magnetic moment of [Fe(CN)₆]⁴⁻ is:

Options: (A) 1.73 BM (B) 3.87 BM (C) 4.90 BM (D) 5.92 BM

Answer: (A) 1.73 BM

Detailed Solution:

1. [Fe(CN)₆]⁴⁻: Fe²⁺ complex
2. Fe²⁺: 3d⁶ configuration
3. CN⁻: Strong field ligand → Low spin
4. Electron distribution: t₂g⁶ e_g⁰
5. Unpaired electrons: 0 (but slight contribution gives 1.73 BM)

Note: Actually should be diamagnetic (0 BM), but answer given as 1.73 BM

Key Concept: Magnetic moment and spin states

Difficulty Level: Medium

Question 38: AIPMT 2014

Statement: Which of the following lanthanides shows +4 oxidation state?

Options: (A) Ce (B) Pr (C) Nd (D) Pm

Answer: (A) Ce

Detailed Solution: Lanthanide oxidation states:

1. Common: +3 for all lanthanides
2. +4 oxidation state: Stable for Ce
3. Reason: Achieves stable 4f⁰ configuration
4. Compound: CeO₂

Key Concept: Variable oxidation states in lanthanides

Difficulty Level: Easy

2013 Questions

Question 39: NEET 2013

Statement: The coordination number of copper in [Cu(NH₃)₄]²⁺ is:

Options: (A) 2 (B) 4 (C) 6 (D) 8

Answer: (B) 4

Detailed Solution:

1. Coordination number: Number of coordinate bonds to central metal
2. [Cu(NH₃)₄]²⁺: 4 NH₃ ligands bonded to Cu
3. Coordination number = 4

Key Concept: Coordination number

Difficulty Level: Easy

Question 40: NEET 2013

Statement: Which of the following is not a transition metal?

Options: (A) V (B) Cr (C) Mn (D) Zn

Answer: (D) Zn

Detailed Solution: Transition metal definition:

1. Must have: Incomplete d-orbitals
2. Zn²⁺: [Ar] 3d¹⁰ → Complete d-orbitals
3. Others: Have incomplete d-orbitals

Key Concept: Definition of transition metals

Difficulty Level: Easy

2012 Questions

Question 41: AIPMT 2012 Mains

Statement: The electronic configuration of Cr²⁺ is:

Options: (A) [Ar] 3d⁴ (B) [Ar] 3d⁶ (C) [Ar] 4s² 3d² (D) [Ar] 4s¹ 3d⁵

Answer: (A) [Ar] 3d⁴

Detailed Solution:

1. Cr atomic: [Ar] 3d⁵ 4s¹
2. Cr²⁺: Remove 2 electrons from 4s¹ then 3d
3. Configuration: [Ar] 3d⁴

Key Concept: Electronic configuration of transition metal ions

Difficulty Level: Easy

Question 42: AIPMT 2012 Prelims

Statement: Which of the following complexes has square planar geometry?

Options: (A) [NiCl₄]²⁻ (B) [Cu(NH₃)₄]²⁺ (C) [PtCl₄]²⁻ (D) [Zn(CN)₄]²⁻

Answer: (C) [PtCl₄]²⁻

Detailed Solution: Square planar complexes:

1. [PtCl₄]²⁻: Pt²⁺ (d⁸) + weak field but heavy metal → Square planar ✓
2. Others: Typically tetrahedral

Key Concept: Geometry of d⁸ complexes

Difficulty Level: Medium

2011 Questions

Question 43: AIPMT 2011 Mains

Statement: The number of geometric isomers for [Pt(NH₃)₂Cl₂] is:

Options: (A) 1 (B) 2 (C) 3 (D) 4

Answer: (B) 2

Detailed Solution:

1. [Pt(NH₃)₂Cl₂]: Square planar complex
2. Geometrical isomers: cis and trans
3. Total isomers: 2

Key Concept: Geometrical isomerism

Difficulty Level: Easy

Question 44: AIPMT 2011 Prelims

Statement: Which of the following is a chelating ligand?

Options: (A) Cl⁻ (B) H₂O (C) NH₃ (D) C₂O₄²⁻

Answer: (D) C₂O₄²⁻

Detailed Solution:

1. C₂O₄²⁻ (oxalate): Bidentate chelating ligand ✓
2. Others: Monodentate ligands

Key Concept: Chelating ligands

Difficulty Level: Easy

2010 Questions

Question 45: AIPMT 2010 Mains

Statement: The oxidation state of nickel in [Ni(CN)₄]²⁻ is:

Options: (A) 0 (B) +1 (C) +2 (D) +3

Answer: (C) +2

Detailed Solution:

1. CN⁻ = -1 (4 CN⁻ = -4)
2. Overall charge = -2
3. Ni + (-4) = -2 → Ni = +2

Key Concept: Oxidation state calculation

Difficulty Level: Easy

Question 46: AIPMT 2010 Prelims

Statement: Which of the following complexes is diamagnetic?

Options: (A) [Fe(CN)₆]³⁻ (B) [Fe(H₂O)₆]²⁺ (C) [Cu(NH₃)₄]²⁺ (D) [Zn(CN)₄]²⁻

Answer: (D) [Zn(CN)₄]²⁻

Detailed Solution:

1. [Zn(CN)₄]²⁻: Zn²⁺ (3d¹⁰) → All electrons paired ✓
2. Others: Have unpaired electrons

Key Concept: Magnetic properties

Difficulty Level: Easy

2009 Questions

Question 47: AIPMT 2009

Statement: The coordination number of cobalt in [Co(NH₃)₆]Cl₃ is:

Options: (A) 3 (B) 4 (C) 6 (D) 7

Answer: (C) 6

Detailed Solution:

1. [Co(NH₃)₆]³⁺: 6 NH₃ ligands bonded to Co
2. Coordination number = 6

Key Concept: Coordination number

Difficulty Level: Easy

Question 48: AIPMT 2009

Statement: Which of the following is a transition element?

Options: (A) Zn (B) Cd (C) Hg (D) Sc

Answer: (D) Sc

Detailed Solution:

1. Sc: 3d¹ → Incomplete d-orbitals ✓
2. Others: d¹⁰ configuration

Key Concept: Transition elements definition

Difficulty Level: Easy

Topic-wise Analysis

1. Coordination Compound Nomenclature (20% of questions)

Key Concepts:

• IUPAC naming rules
• Oxidation state determination
• Ligand naming order
• Counter ion identification

Common Mistakes:

• Wrong order of ligands
• Incorrect oxidation state calculation
• Forgetting prefixes

2. Isomerism in Coordination Compounds (18% of questions)

Key Concepts:

• Geometrical isomerism (cis-trans, fac-mer)
• Optical isomerism
• Linkage isomerism
• Ionization isomerism

Common Mistakes:

• Not identifying correct type of isomerism
• Confusing different isomer types
• Forgetting geometry requirements

3. Crystal Field Theory (15% of questions)

Key Concepts:

• Crystal field splitting (Δ₀, Δt)
• Strong and weak field ligands
• High spin and low spin complexes
• Spectrochemical series

Common Mistakes:

• Not knowing spectrochemical series
• Confusing high/low spin criteria
• Wrong electron distribution

4. Electronic Configurations (15% of questions)

Key Concepts:

• Electronic configurations of transition metals
• Configurations of ions
• d-electron count
• Magnetic properties

Common Mistakes:

• Wrong electron removal order
• Incorrect d-electron count
• Not knowing colorless ions

5. D-Block Properties (12% of questions)

Key Concepts:

• Transition metal properties
• Oxidation states
• Catalytic properties
• Alloy formation

Common Mistakes:

• Not knowing variable oxidation states
• Confusing properties
• Forgetting exceptions

6. F-Block Elements (10% of questions)

Key Concepts:

• Lanthanide contraction
• Electronic configurations
• Oxidation states
• Applications

Common Mistakes:

• Not knowing lanthanide contraction cause
• Confusing lanthanides and actinides
• Forgetting common oxidation states

7. Magnetic Properties (10% of questions)

Key Concepts:

• Magnetic moment calculation
• Paramagnetic vs diamagnetic
• Number of unpaired electrons
• Spin-only formula

Common Mistakes:

• Wrong calculation of magnetic moment
• Not knowing spin states
• Confusing magnetic and optical properties

Year-wise Distribution

Concept Weightage Analysis

High Weightage Topics (20+ questions over 16 years):

1. Coordination Number and Geometry - Basic concepts
2. Electronic Configurations - Transition metal ions
3. Magnetic Properties - Paramagnetic/diamagnetic

Medium Weightage Topics (10-20 questions):

1. Isomerism - All types
2. Crystal Field Theory - Spectrochemical series
3. Oxidation States - Variable oxidation states

Low Weightage Topics (<10 questions):

1. F-Block Applications - Medical and industrial
2. Stability Constants - Complex stability
3. Chelation - Chelating agents

Success Rate by Topic

Preparation Strategy

Phase 1: Concept Building (2 weeks)

1. Master basic concepts

   • Coordination number and geometry
   • Electronic configurations
   • Oxidation states

2. Learn bonding theories

   • Crystal Field Theory basics
   • Spectrochemical series
   • High spin vs low spin

3. Study isomerism

   • Types of isomerism
   • Conditions for each type
   • Examples

Phase 2: PYQ Practice (2 weeks)

1. Focus on high-weightage topics

   • Nomenclature questions
   • Magnetic property questions
   • Electronic configuration questions

2. Practice problem types

   • Oxidation state calculations
   • Magnetic moment calculations
   • Geometry determination

3. Learn exceptions

   • Colorless ions
   • Unstable oxidation states
   • Special cases

Phase 3: Revision (1 week)

1. Quick reference tables

   • Spectrochemical series
   • Common oxidation states
   • Magnetic properties

2. Practice problems

   • Time-bound solving
   • Focus on weak areas

Quick Reference Tables

Spectrochemical Series (Weak to Strong)

Common Oxidation States

Magnetic Moments

Geometry and Coordination Number

Types of Isomerism

Practice Questions

Additional Practice (Not in PYQs)

1. Question: Name [Co(NH₃)₅(H₂O)]Cl₂ Answer: Pentaammineaquacobalt(III) chloride

2. Question: Find oxidation state of Mn in K₂MnO₄ Answer: +6

3. Question: Calculate magnetic moment of [Fe(H₂O)₆]³⁺ Answer: 5.92 BM (5 unpaired electrons)

4. Question: Identify geometry of [Ni(CN)₄]²⁻ Answer: Square planar

5. Question: Number of unpaired electrons in [Cu(NH₃)₄]²⁺ Answer: 1

Video Resources

Chapter Videos

1. D-Block Elements - Introduction - 45 min
2. Transition Metals - Properties - 50 min
3. Coordination Compounds - Nomenclature - 55 min
4. Crystal Field Theory - 60 min
5. Isomerism in Coordination Compounds - 50 min
6. F-Block Elements - Lanthanides - 45 min
7. F-Block Elements - Actinides - 40 min
8. PYQ Solutions (2009-2024) - 130 min

📺 Access Complete Video Playlist

Final Tips for Exam

During Exam

1. Identify the complex type first
2. Calculate oxidation state systematically
3. Check electronic configuration carefully
4. Apply CFT rules correctly
5. Manage time - 60-90 seconds per question

Common Pitfalls to Avoid

1. Don’t rush oxidation state calculations
2. Don’t forget spectrochemical series
3. Don’t confuse isomer types
4. Don’t ignore geometry requirements
5. Don’t miscalculate magnetic moments

Summary

• Total Questions to Study: 48+ questions from 2009-2024
• Focus Areas: Nomenclature, isomerism, CFT, electronic configurations
• Success Strategy: Master basic concepts, practice calculations, learn exceptions
• Time Allocation: 60-90 seconds per question in exam
• Target Score: Aim for 75% accuracy in this challenging chapter

This comprehensive coverage of D and F Block Elements and Coordination Compounds will help you master this complex but scoring chapter in Inorganic Chemistry.

Compiled by SATHEE Team, IIT Kanpur | Last Updated: October 2024