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d and f Block elements WBCHSE Class 12 MCQ & Practice Questions

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d and f Block elements Revision Guide for WBCHSE Class 12 Chemistry

d and f Block elements is part of WBCHSE Class 12 Chemistry preparation. A strong revision plan should combine concept review with exam-style questions so that definitions, relationships, calculations and exceptions are recalled accurately.

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Top 20 d and f Block elements MCQs with Answers

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WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

1. Transition element-এর characteristic electronic configuration সাধারণত?

  • A. (n−1)d1–10 ns0–2
  • B. ns2np6 only
  • C. 1s2 only
  • D. nf14 always
Answer: A
Explanation: Transition series-এ differentiating electron (n−1)d subshell-এ প্রবেশ করে।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

2. Zn সাধারণত transition element হিসেবে গণ্য হয় না কেন?

  • A. Zn metal নয়
  • B. Zn ও Zn2+ উভয়ের d-subshell পূর্ণ d10
  • C. Zn coloured
  • D. Zn radioactive
Answer: B
Explanation: Transition element-এর atom বা common ion-এ incomplete d-subshell থাকা উচিত; Zn/Zn2+ d10।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

3. Transition metal ions প্রায়ই coloured কেন?

  • A. d–d electronic transition
  • B. সব ion black
  • C. s-orbital absent
  • D. nucleus colour
Answer: A
Explanation: Partially filled d-orbitals ligand field-এ split হয়ে visible light absorption-এর d–d transition দেয়।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

4. Sc3+ সাধারণত colourless কেন?

  • A. d0 configuration
  • B. d5 configuration
  • C. d10 only
  • D. f7
Answer: A
Explanation: Sc3+ = d0; d–d transition সম্ভব নয়, তাই সাধারণত colourless।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

5. Ti3+ configuration কী?

  • A. d0
  • B. d1
  • C. d2
  • D. d10
Answer: B
Explanation: Ti Z=22: [Ar]3d2 4s2; Ti3+ → [Ar]3d1।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

6. Mn2+ high-spin ion-এ unpaired electron কত?

  • A. 1
  • B. 3
  • C. 5
  • D. 0
Answer: C
Explanation: Mn2+ = 3d5; high spin free ion-এ পাঁচটি d orbital-এ পাঁচ unpaired electron।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

7. KMnO4-এ Mn-এর oxidation state?

  • A. +2
  • B. +4
  • C. +6
  • D. +7
Answer: D
Explanation: K=+1, O4=−8; Mn=+7।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

8. K2Cr2O7-এ Cr-এর oxidation state?

  • A. +3
  • B. +4
  • C. +6
  • D. +7
Answer: C
Explanation: 2K=+2, 7O=−14; 2Cr=+12, প্রতিটি Cr=+6।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

9. Acidic medium-এ permanganate ion সাধারণত কীতে reduce হয়?

  • A. MnO2
  • B. Mn2+
  • C. MnO4^2−
  • D. Mn metal
Answer: B
Explanation: Acidic medium-এ MnO4− + 8H+ +5e− → Mn2+ +4H2O।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

10. Neutral/weak alkaline medium-এ KMnO4 প্রায়ই কী দেয়?

  • A. Mn2+
  • B. MnO2
  • C. Mn metal
  • D. MnF7
Answer: B
Explanation: Neutral/weak alkaline medium-এ permanganate MnO2 brown precipitate-এ reduce হতে পারে।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

11. Dichromate ion-এর রং?

  • A. বেগুনি
  • B. কমলা
  • C. সবুজ
  • D. নীল
Answer: B
Explanation: Cr2O7^2− orange; chromate CrO4^2− yellow।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

12. Chromate ion-এর রং?

  • A. হলুদ
  • B. কমলা
  • C. বেগুনি
  • D. সাদা
Answer: A
Explanation: CrO4^2− characteristic yellow colour।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

13. Lanthanoid contraction-এর মূল কারণ?

  • A. 4f electrons-এর poor shielding
  • B. 5d electrons-এর perfect shielding
  • C. nuclear charge কমা
  • D. atom gain proton না
Answer: A
Explanation: Series-এ nuclear charge বাড়ে কিন্তু 4f shielding দুর্বল, ফলে atomic/ionic radii ধীরে কমে।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

14. Lanthanoids-এর সবচেয়ে common oxidation state?

  • A. +1
  • B. +2
  • C. +3
  • D. +7
Answer: C
Explanation: Most lanthanoids stable +3 state দেখায়।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

15. Actinoids lanthanoids-এর তুলনায় বেশি variable oxidation state কেন?

  • A. 5f, 6d, 7s energies কাছাকাছি
  • B. actinoids inert gas
  • C. 4f absent only
  • D. all d10
Answer: A
Explanation: 5f/6d/7s orbitals energetically comparable হওয়ায় বহু electrons bonding-এ অংশ নিতে পারে।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

16. Transition metals ভালো catalyst কেন?

  • A. variable oxidation states ও adsorption ability
  • B. সব inert
  • C. no d-electrons
  • D. low melting always
Answer: A
Explanation: Variable oxidation state intermediate গঠন ও surface adsorption catalysis-এ সাহায্য করে।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

17. Transition metals-এর magnetic property প্রধানত কিসের উপর নির্ভর করে?

  • A. unpaired electrons
  • B. paired s-electrons only
  • C. atomic mass only
  • D. colour only
Answer: A
Explanation: Paramagnetism unpaired electron count-এর সঙ্গে সম্পর্কিত।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

18. d5 high-spin configuration-এর spin-only magnetic moment প্রায় কত BM?

  • A. 1.73
  • B. 2.83
  • C. 4.90
  • D. 5.92
Answer: D
Explanation: μ = √[n(n+2)] with n=5 = √35 ≈ 5.92 BM।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

19. Cu+ সাধারণত colourless কেন?

  • A. d10 configuration
  • B. d9
  • C. d5
  • D. f14 only
Answer: A
Explanation: Cu+ = [Ar]3d10; d–d transition অনুপস্থিত।

WBCHSE Class 12 Chemistry · d and f Block elements · Very Hard

20. Cu2+ সাধারণত coloured কেন?

  • A. d9 configuration
  • B. d10
  • C. d0
  • D. s2 only
Answer: A
Explanation: Cu2+ = 3d9; ligand field-এ d–d transitions সম্ভব।

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d and f Block elements Frequently Asked Questions

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