d and f Block Elements Most Important Questions for Class 12th Boards

With the CBSE Class 12th Chemistry exam scheduled on 28 February 2026, students now need focused, high-yield revision instead of lengthy theory reading. These carefully selected d and f Block Elements most important questions are designed from previous year questions (PYQs), exam patterns, and frequently tested concepts.

This question-based revision approach helps you quickly recall electronic configurations, oxidation states, redox behaviour, and properties of transition and inner transition elements. Solving these questions before the exam strengthens conceptual clarity, improves answer presentation, and increases confidence for both short-answer and long-answer sections.

d and f Block Elements Most Important Questions

Here are the d and f Block Elements Most Important Questions given below: 

1. Transition metals are known to form interstitial compounds. Formation of interstitial compounds makes the transition metal more hard, more soft, more ductile, or more metallic?
   
   

2. Assertion–Reason Question:
   Assertion — Zr and Hf have almost similar atomic radii.
   Reason — This is due to lanthanoid contraction.
   Choose the correct option.
   
   

3. Why is Ce³⁺ easily oxidised to Ce⁴⁺?
   
   

4. The standard reduction potential value for Mn²⁺ to Mn is negative. Explain why.
   
   

5. Which element of the 3d series has the lowest enthalpy of atomisation and why?
   
   

6. What happens when chromate ions react with acid? Write the reaction.
   
   

7. Why are Zn, Cd and Hg considered soft metals?
   
   

8. Which section should be attempted first in the exam for better time management?
   
   

9. Why is permanganate used as a titrant?
   
   

10. Why is permanganate titration not carried out in the presence of HCl?
    
    

11. Which actinoid has the electronic configuration 5f⁷ 7s²?
    
    

12. Which lanthanoid has a 4f¹⁴ electronic configuration in the +3 oxidation state?
    
    

13. Which lanthanoid shows a +4 oxidation state?
    
    

14. Which of the following sets correctly represents the increasing paramagnetic nature of the ions: Ti³⁺, Cr³⁺, Mn²⁺, Fe²⁺?
    
    

15. MnO₂ is fused with KOH in the presence of KNO₃ as an oxidising agent to give a dark green compound A.
    (a) Identify compound A.
    (b) Compound A disproportionates in acidic solution to give a purple compound B. Identify B.
    (c) What happens when compound B reacts with iodide ions in alkaline medium?
    (d) What happens when compound B reacts with iodide ions in acidic medium?
    
    

16. Using the given standard electrode potential data, which is the stronger reducing agent in aqueous solution: Cr²⁺ or Fe²⁺?

17. Why does H₂O act as a weak ligand and how does it affect crystal field splitting in an octahedral complex?
    
    

18. How does energy change when three electrons occupy the t₂g orbitals in a d³ configuration?
    
    

19. Why do electrons occupy e_g orbitals in a d⁵ configuration with a weak ligand?
    
    

20. Which ion is most stable in the +2 oxidation state and why?
    
    

21. Why do transition metals form alloys?
    
    

22. Why is Mn₂O₃ basic whereas Mn₂O₇ is acidic?
    
    

23. What happens when Mn₂O₇ reacts with water?
    
    

24. Why is Eu²⁺ a strong reducing agent?

25. Complete and balance the reaction:
    MnO₂ + K + O₂ → ?
    
    

26. Complete and balance the reaction in acidic medium:
    MnO₄⁻ + I⁻ + H⁺ → ?
    
    

27. Complete and balance the reaction in acidic medium:
    Cr₂O₇²⁻ + Sn²⁺ + H⁺ → ?
    
    

28. Explain the method of balancing redox reactions using oxidation number change.
    
    

29. Why is Eu²⁺ a strong reducing agent?
    
    

30. Why does scandium show only +3 oxidation state?
    
    

31. Why are some transition metal ions colourless?
    
    

32. Why is MnO basic whereas Mn₂O₇ is acidic?
    
    

33. What is the general electronic configuration of lanthanides?
    
    

34. When is a metal ion most stable in +2 oxidation state?

Benefits of Solving d and f Block Elements Most Important Questions

Practicing these questions helps you identify frequently asked board concepts and improves retention of electronic configuration trends. 

• It strengthens conceptual clarity in oxidation states, redox reactions, and coordination behaviour — topics that often carry direct marks in the exam.

• Regular practice also improves speed and answer accuracy, which is crucial for completing the paper on time. Since these questions are PYQ-oriented, they train you to recognise patterns in board-level questions and reduce exam anxiety.

• Most importantly, this focused revision strategy ensures that even in the final days before the exam, you are studying high-return topics instead of revising randomly.