Practise 21 real Federal Board questions on Transition elements from 2023 to 2026. See the answer and explanation as soon as you answer.
Transition elements is one of the 19 main chapters in our Federal Board FSC Chemistry question bank (12th class), and about 4% of its real questions come from it. Tayyari Karo has 21 real questions on this chapter from 2023 to 2026; 5 are multiple choice and marked instantly, and the rest are short and long questions with a model answer. By difficulty: 13 medium, 4 easy, 4 hard.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
These are real past-paper questions. Think of your answer first, then open the explanation.
Ligands form bonds with transition metals by:
Answer: D. Donating lone pairs of electrons
Ligands are Lewis bases that donate a lone pair of electrons into the metal's empty d-orbitals, forming coordinate (dative) bonds.
The expected shape of [Fe(H₂O)₆]⁺² based on its coordination number is:
Answer: B. Octahedral
Six water ligands around Fe²⁺ give a coordination number of 6, corresponding to an octahedral geometry.
Which transition metal is used as a catalyst in Haber's process?
Answer: D. Fe
Finely divided iron (Fe) is the catalyst used in the Haber process for ammonia synthesis.
The geometry of complex ion [Cr(en)₃]³⁺ is:
Answer: A. Octahedral
Three bidentate ethylenediamine (en) ligands provide 6 donor N atoms around Cr³⁺, giving an octahedral geometry.
The color of dichromate solution is:
Answer: B. Orange
The dichromate ion, Cr₂O₇²⁻, gives an orange colour in solution (chromate CrO₄²⁻ is yellow).
Given the following half-cell reactions: Fe³⁺+e⁻→Fe²⁺ (E°=+0.77V), Zn²⁺+2e⁻→Zn (E°=−0.76V). Identify the oxidation and reduction reactions and calculate E° of cell.
Since Fe³⁺/Fe²⁺ has the higher (more positive) E°, it is the cathode (reduction): Fe³⁺ + e⁻ → Fe²⁺
Zn/Zn²⁺ has the lower E°, so it is reversed as the anode (oxidation): Zn → Zn²⁺ + 2e⁻
E°cell = E°cathode − E°anode = 0.77 − (−0.76) = +1.53 V
Why group II-B and III-B are considered as non-typical transition elements?
Typical transition elements must have a partially filled d subshell in at least one common oxidation state. Group II-B (Zn, Cd, Hg) have a completely filled d¹⁰ configuration in both the metal and their common +2 ions — so they lack variable oxidation states, coloured ions, and catalytic activity typical of transition metals. Group III-B (Sc, Y, La) readily lose their single d electron to form a completely empty d⁰ ion (+3 state only) — again colourless, with no variable oxidation states. Since neither group ever has a partially-filled d subshell in its ions, both are classed as non-typical transition elements.
Identify ligands, co-ordination number and geometry of the following complex ion [Co(en)₂Cl₂]⁺
Ligands: ethylenediamine (en) — a neutral, bidentate ligand (×2), and chloride ion (Cl⁻) — a monodentate ligand (×2).
Coordination number: each en contributes 2 donor N atoms (2×2=4) plus 2 Cl⁻ (2×1=2), giving a total of 6.
Geometry: Octahedral (can exist as cis or trans isomers).
| Session | Questions |
|---|---|
| 2026 Annual | 6 |
| 2025 1st Annual | 4 |
| 2025 2nd Annual | 4 |
| 2024 Annual | 4 |
| 2023 Annual | 3 |
21 real Federal Board (FBISE) Chemistry questions on Transition elements from 2023 to 2026, for 12th class. Each one shows the session it came from.
No. We could not find an official FBISE marking scheme for these papers, so the answers and explanations are written by Tayyari Karo for practice. Check anything important with your teacher or textbook.
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