Transition Elements

Transition Elements MDCAT MCQs with answers

34 past paper MCQs from Chemistry unit 12, Transition Elements, across 1 topic. They are arranged topic by topic; bigger topics show a sample here and link to their full set and to study notes. Tap “Show answer” for the correct option and a short solution.

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Electronic Structure of d-Block Elements

1.In which pair does one element have all unpaired $d$ orbitals while the other has all paired $d$ orbitals? (MDCAT 2022)

  1. Cu and Zn
  2. Cr and Fe
  3. Cr and Zn
  4. Mn and Co
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Correct answer: (c) Cr and Zn

Chromium is $3d^5$, with every $d$ orbital singly filled, and zinc is $3d^{10}$, with every one of them full.

2.Which of the following electronic configurations is correct for $_{24}\mathrm{Cr}$? (MDCAT 2023)

  1. $[\mathrm{Ar}]3d^54s^1$
  2. $[\mathrm{Ar}]3d^44s^2$
  3. $[\mathrm{Ar}]3d^64s^0$
  4. $[\mathrm{Ar}]3d^34s^2$
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Correct answer: (a) $[\mathrm{Ar}]3d^54s^1$

One electron moves from $4s$ to $3d$ to give the more stable half-filled $d$ set.

3.Which of the following transition metals shows a $3d^5$ configuration in its $+2$ oxidation state? (MDCAT 2023)

  1. $\mathrm{Cu^{2+}}$
  2. $\mathrm{Fe^{2+}}$
  3. $\mathrm{Mn^{2+}}$
  4. $\mathrm{Zn^{2+}}$
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Correct answer: (c) $\mathrm{Mn^{2+}}$

Manganese is $[\mathrm{Ar}]3d^54s^2$, so losing the two $4s$ electrons leaves $3d^5$.

4.The electronic configuration of chromium (proton number 24) is: (MDCAT 2024)

  1. $[\mathrm{Ar}]3d^44s^2$
  2. $[\mathrm{Ar}]3d^54s^1$
  3. $[\mathrm{Ar}]3d^54s^2$
  4. $[\mathrm{Ar}]3d^64s^0$
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Correct answer: (b) $[\mathrm{Ar}]3d^54s^1$

A half-filled $3d$ set with one $4s$ electron is the more stable arrangement.

5.Which of the following is NOT a property of transition elements? (MDCAT 2024)

  1. high melting points
  2. good conductors of electricity
  3. hard metals
  4. their ions and compounds are colourless
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Correct answer: (d) their ions and compounds are colourless

Transition metal ions are typically coloured, because of $d$-$d$ electron transitions.

6.Which one of the following is a coinage metal (UHS MDCAT 2025)

  1. Pd
  2. Cu
  3. Cd
  4. Hg
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Correct answer: (b) Cu

Copper, silver and gold are the coinage metals.

7.Which of the following is NOT an Alloy (UHS MDCAT 2024)

  1. Steel
  2. Brass
  3. Bronze
  4. Graphite
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Correct answer: (d) Graphite

Graphite is an element, not a mixture of metals.

8.Electronic configuration of chromium (Proton number 24) is: (UHS MDCAT 2024)

  1. [Ar] 3d4 4s2
  2. [Ar] 3d5 4s2
  3. [Ar] 3d5 4s1
  4. [Ar] 3d6 4s2
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Correct answer: (c) [Ar] 3d5 4s1

A half filled d subshell is stable, so chromium is $[\mathrm{Ar}]3d^5 4s^1$.

9.Cu2+ salt solution is blue in colour due to transition of electrons from (KMU MDCAT 2024)

  1. d to d orbital
  2. p to d orbital
  3. p to p orbital
  4. s to p orbital
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Correct answer: (a) d to d orbital

The d subshell is split by the ligands, and an electron moving between the split levels absorbs visible light.

10.Potassium ferrocyanide is which type of salt? (KMU MDCAT 2024)

  1. Complex
  2. Double
  3. Mixed
  4. Normal
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Correct answer: (a) Complex

It gives no simple iron ions in solution, because the iron is held in the complex ferrocyanide ion.

11.Q.99 Which of the following complex show a tetrahedral geometry? (UHS MDCAT 2023)

  1. [Fe(CO)5]
  2. [Cu(CN)4]-2
  3. [Au(Cl)4]-
  4. [Pt(NH3)4]+2
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Correct answer: (b) [Cu(CN)4]-2

Four ligands round a copper(I) centre with no d-orbital preference give a tetrahedron.

12.In which pair one has all Unpaired d orbitals while other have all paired d orbitals ? (UHS MDCAT 2023)

  1. Cu and Zn
  2. Cr and Fe
  3. Cr and Zn
  4. Mn and Co
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Correct answer: (c) Cr and Zn

Chromium is $3d^5$, all five unpaired; zinc is $3d^{10}$, all paired.

13.The transition element which doesn’t show variable valency: (SZABMU MDCAT 2023)

  1. Cu
  2. Sc
  3. Zn
  4. Cr
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Correct answer: (c) Zn

Zinc has a full d subshell, so it can only give up its two 4s electrons.

14.The binding energy of transition metals increases upto group: (SZABMU MDCAT 2023)

  1. II B
  2. IV B
  3. III B
  4. VI B
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Correct answer: (d) VI B

More unpaired d electrons mean stronger metallic bonding, and that peaks around group VI B.

15.Which of the following transition metal show 3d5 configuration in its +2-oxidation state? (UHS MDCAT 2023)

  1. Cu+2
  2. Fe+2
  3. Mn+2
  4. Zn+2
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Correct answer: (c) Mn+2

Manganese(II) has lost its two 4s electrons, leaving a half filled $3d^5$ subshell.

16.Coinage metals belong to which group of the periodic table? (PMC MDCAT 2022)

  1. 1B
  2. 2B
  3. 3B
  4. 3A
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Correct answer: (a) 1B

Copper, silver and gold make up group IB.

17.An element that forms interstitial compounds is ______. (PMC MDCAT 2022)

  1. C
  2. F
  3. Cs
  4. Rb
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Correct answer: (a) C

Small atoms such as carbon fit into the holes of a metal lattice to give interstitial compounds.

18.Which element shows maximum oxidation state? (PMC MDCAT 2022)

  1. Cu
  2. Zn
  3. Cr
  4. Mn
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Correct answer: (d) Mn

Manganese can use all seven of its outer electrons, so it reaches $+7$.

19.The transition element which shows fixed 2+ oxidation state in its compound is: (PMC MDCAT 2022)

  1. Zn
  2. Fe
  3. Cu
  4. Mn
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Correct answer: (a) Zn

Zinc has a full d subshell, so it can only lose its two 4s electrons.

20.The color of Zn2+ compounds is: (PMC MDCAT 2022)

  1. Yellow
  2. Black
  3. Blue
  4. Colorless
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Correct answer: (d) Colorless

Zinc has no partly filled d subshell, so there are no d-d transitions and its salts are white.

21.How many unpaired electrons are there in Co2+ ion? (PMC MDCAT 2022)

  1. 2
  2. 3
  3. 4
  4. 7
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Correct answer: (b) 3

Cobalt(II) is $3d^7$, which leaves three electrons unpaired.

22.Transition elements form which bond with ligands? (PMC MDCAT 2022)

  1. Covalent
  2. Ionic
  3. Metallic
  4. Coordinate Covalent
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Correct answer: (d) Coordinate Covalent

The ligand donates both electrons of the bond to the empty d orbital of the metal.

23.Melting and boiling point of transition elements is higher due to? (PMC Practice 2021)

  1. Higher binding energy
  2. Strong metallic bonding
  3. Hardness
  4. All of these
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Correct answer: (b) Strong metallic bonding

Unpaired d electrons take part in the bonding as well as the s electrons, so the metallic bond is strong.

24.D block elements are also called as ____ ? (PMC Practice 2021)

  1. Rare earth elements
  2. Outer transition elements
  3. Inner transition elements
  4. Typical transition elements
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Correct answer: (b) Outer transition elements

The d block are the outer transition elements; the f block are the inner ones.

25.F-block elements are called? (PMC Practice 2021)

  1. Inner transition
  2. Outer transition
  3. Both
  4. None
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Correct answer: (a) Inner transition

The f block are the inner transition elements.

26.[Fe (CN)6]4- is called as ______. (PMC Practice 2021)

  1. Complex compound
  2. Transition element ion
  3. Anion
  4. Complex anion
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Correct answer: (d) Complex anion

It is a complex ion carrying a net negative charge, that is a complex anion.

27.The transition element which does not show variable valency is: (PMC MDCAT 2020)

  1. Cu
  2. Sc
  3. Zn
  4. Cr
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Correct answer: (c) Zn

Zinc has a full d subshell, so it can only give up its two 4s electrons.

28.In 3rd series of transition elements, paramagnetic behaviour is maximum for Mn +2 and : (PMC MDCAT 2020)

  1. Cr3+
  2. Ti3+
  3. V3+
  4. Zn2+
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Correct answer: (a) Cr3+

Chromium(III) and manganese(II) both have half filled or nearly half filled d subshells with the most unpaired electrons.

29.Copper is a typical transition metal. Its atomic number is 29. In which oxidation state does it have a partially filled orbital in d-subshell? (UHS MDCAT 2019)

  1. Cu
  2. Cu+
  3. Cu-
  4. Cu2+
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Correct answer: (d) Cu2+

Copper(I) is $3d^{10}$ and full; copper(II) is $3d^9$, which is partly filled.

30.The shape of [Co(NH3)6]3+ complex is: (UHS MDCAT 2018)

  1. Linear
  2. Square planar
  3. Tetrahedral
  4. Octahedral
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Correct answer: (d) Octahedral

Six ligands round a central ion take the corners of an octahedron.

31.Ligands having two lone pair of electrons for donation to the central transition metal ion are known as: (UHS MDCAT 2018)

  1. Polydentate ligands
  2. Monodentate ligand
  3. Bidentate ligands
  4. Hexadentate ligands
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Correct answer: (c) Bidentate ligands

A ligand with two donor atoms is bidentate.

32.How many ligands does K4[Fe(CN)6] contains: (UHS MDCAT 2017)

  1. 4
  2. 7
  3. 6
  4. 5
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Correct answer: (c) 6

Six cyanide ions surround the iron, so there are six ligands.

33.Identify the element that has maximum oxidation states: (UHS MDCAT 2017)

  1. Zinc
  2. Chromium
  3. Vanadium
  4. Manganese
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Correct answer: (d) Manganese

Manganese can use all seven of its outer electrons, reaching $+7$.

34.The anomalous electronic configuration shown by chromium and copper among 3-d series of elements is due to: (UHS MDCAT 2016)

  1. Colour of ions of these metals
  2. Variable oxidation states of metals
  3. Stability associated with this configuration
  4. Complex formation tendency of metals
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Correct answer: (c) Stability associated with this configuration

A half filled or filled d subshell is unusually stable, so an s electron moves across.

Electronic Structure of d-Block Elements notes →

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