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Most Repeated MDCAT Chemistry: D and f Block Elements MCQs
The most repeated D and f Block Elements questions in MDCAT Chemistry, measured from 377 real past papers. D and f Block Elements contributed 254 questions across those papers, and 10 distinct questions recurred with the same verified answer across 2 or more different exam years — listed below (ranked by how many years each recurs in), with the answer, an explanation, and the exact years.
Measured from 377 real past papers · updated July 2026
Why D and f Block Elements is a high-yield MDCAT Chemistry topic
Out of 254 real Chemistry questions attributed to D and f Block Elements across 377 MDCAT past papers, 10 distinct questions came back with the same correct answer in 2 or more different exam years (the recurrences here span 2014–2024, 9 distinct exam years). A question the examiners have reused verbatim is far more likely to appear again than one asked only once — which is exactly why working through this list first is one of the highest-return ways to revise MDCAT Chemistry. 1 of them recurred in 3 or more separate years.
Most repeated in this topic
“Which of the following is a non typical transition element?”
Appeared in 3 exam years (2018, 2020, 2021) — always with the same answer. It is the first question below.
How to use this list
Every question below shows the verified correct answer, a short explanation, and the exact past-paper years it appeared in — with the most-repeated ones first. Read the explanation even when you know the answer, since MDCAT often reuses the concept with reworded options. When you have these 10 down cold, drill the full topic with fresh questions in the MDCAT MCQ practice bank.
How we measured “most repeated”
We parsed 377 real MDCAT past papers and grouped questions that are effectively the same. A question counts as repeated only when the same correct answer recurs in 2 or more distinct exam years — not merely a similar topic or a lucky guess. Questions that appeared only once are excluded, so nothing here is padding. See the full method and subject-by-subject numbers on the MDCAT repetition study.
- 1Repeated in 3 yearsD and f Block Elements
Which of the following is a non typical transition element?
- ACr
- BMn
- CZn✓
- DFe
Explanation
Zinc (Zn) is considered a non-typical transition element because it does not exhibit typical transition metal properties like variable oxidation states or the formation of colored compounds. It has a full d subshell in its electron configuration, which sets it apart from other transition elements.
Appeared in the past papers of: 2018, 2020, 2021
- 2Repeated in 2 yearsD and f Block Elements
Which of the following has the maximum number of unpaired electrons?
- AFe²⁺✓
- BMn4⁺
- CCr³⁺
- DCu²⁺
Explanation
The electron configuration of Fe²⁺ is [Ar] 3d⁶. In the 3d orbital, there are 4 unpaired electrons.
Appeared in the past papers of: 2023, 2024
- 3Repeated in 2 yearsD and f Block Elements
NH2 (amine) is an example of:
- ANeutral ligand✓
- BAnionic ligand
- CCationic ligand
- DNone of the above
Explanation
This is the correct answer. An amine (NH2) is a neutral ligand because it does not carry a net charge.
Appeared in the past papers of: 2023, 2024
- 4Repeated in 2 yearsD and f Block Elements
The transition element which doesn't show variable valency?
- ACu
- BSc
- CZn✓
- DCr
Explanation
The answer to the question should be option C because Zinc does not show the variable valency as elements of the d-block. After all, the d-orbital is full. Its outer electronic configuration is 3d^10 4s^2 So, they tend to lose only 2 electrons from its outermost shell. Hence, only show a valency of +2 and no variable valency.
Appeared in the past papers of: 2022, 2024
- 5Repeated in 2 yearsD and f Block Elements
Chromium compounds in which oxidation state of chromium is 2+ behaves as a:
- AStrong oxidizing agent
- BStrong reducing agent✓
- CVery weak oxidizing agent
- DVery weak reducing agent
Explanation
The correct answer is that chromium compounds in which the oxidation state of chromium is 2+ behave as strong reducing agents. This is due to their ability to easily donate electrons, thereby reducing other substances and becoming oxidized themselves to higher oxidation states such as +3, +4, or +6.Option A, a strong oxidizing agent, is incorrect because chromium in the +2 state is more likely to be oxidized than to oxidize other substances. Option C, a very weak oxidizing agent, is incorrect for similar reasons, as it downplays the reducing capability of chromium(II).
Appeared in the past papers of: 2015, 2016
- 6Repeated in 2 yearsD and f Block Elements
The electronic transition that is involved in the visible region is:
- Aσ - σ
- Bd – d✓
- Cπ - π
- Dπ - σ
Explanation
d-d transitions are electronic transitions that occur between the molecular orbitals that are mostly metallic in character; specifically between the d-orbitals of a transition metal complex. When electronic transitions occur between these orbitals, the color observed is complementary to the wavelengths absorbed in the visible region.
Appeared in the past papers of: 2015, 2016
- 7Repeated in 2 yearsD and f Block Elements
Potassium ferrocyanide is a:
- ANormal Salt
- BMixed Salt
- CDouble Salt
- DComplex Salt✓
Explanation
Potassium ferrocyanide, with the chemical formula K4Fe(CN)6, is considered a double salt. It is formed by the combination of two different salts: potassium cyanide (KCN) and iron(II) cyanide (Fe(CN)2). Therefore, option c is correct.
Appeared in the past papers of: 2022, 2024
- 8Repeated in 2 yearsD and f Block Elements
Which pair of ions have five unpaired d-electrons?
- AFe+2 and Mn+2
- BFe+2 and Mn+3
- CFe+3 and Mn+3
- DFe+3 and Mn+2✓
Appeared in the past papers of: 2022, 2023
- 9Repeated in 2 yearsD and f Block Elements
Electric cookers have a coating that protects them against fire:
- AHeavy lead
- BMagnesium oxide✓
- CZinc oxide
- DSodium sulphate
Explanation
Magnesium Oxide (MgO) has a high melting point that makes it so that it doesn't burn under low pressure and high temperature.
Appeared in the past papers of: 2014, 2015
- 10Repeated in 2 yearsD and f Block Elements
Infrared lamps are used in restaurants and cafeterias to keep food warm. The infrared radiation is strongly absorbed by water, raising its temperature and that of the food. If the wavelength of infrared radiation is assumed to be 1500nm, then the number of photons per second of infrared radiation produced by an infrared lamp that consumes energy of the rate of 100 watt and is 12% efficient will be:
- A4 x 1010
- B9 x 1019✓
- C11 x 1012
- D15 x 104
Explanation
To calculate the number of photons per second of infrared radiation produced by the infrared lamp, we can use the energy and efficiency of the lamp. The energy emitted per second is equal to the power, which is 100 joules/second. Effective energy emitted per second = 0.12 * 100 joules/second = 12 joules/second The energy of a single photon is given by Planck's equation: E = hc/λ Where E is the energy of a photon, h is Planck's constant (6.626 x 10^-34 J·s), c is the speed of light (3.0 x 10^8 m/s), and λ is the wavelength of the radiation (1500 nm = 1.5 x 10^-6 m).
Appeared in the past papers of: 2014, 2015