d And f Block Elements Class 12 MCQ Question 1.

Electronic configuration of a transition element X in +3 oxidation state is [Ar]3d⁵. What is its atomic number?

(A) 25
(B) 26
(C) 27
(D) 24
Answer:
(B) 26

Explanation:
It is formed by the loss of 3 electrons, S the configuration of element X is [4r] 3d⁶4s². Therefore, Atomic number = 26.

d And f Block Elements MCQ Chapter 8 Question 2.

The electronic configuration of Cu(II) is 3d9 whereas that of Cu(I) is 3d¹⁰ Which of the following is correct?

(A) Cu (II) is more stable.
(B) Cu (II) is less stable.
(C) Cu (I) and Cu(II) are equally stable.
(D) Stability of Cu(I) and Cu(II) depends on nature of copper salts.
Answer:
(A) Cu (II) is more stable.

Explanation:
Cu(II) is more stable due to nuclear charge of Cu.

MCQ On d And f Block Elements Chapter 8 Question 3.

When KMnO₄ solution is added to oxalic acid solution, the de colourisation is slow in the beginning but becomes instantaneous after some time because

(A) CO₂ is formed as the product.
(B) Reaction is exothermic.
(C) MnO₂” catalyses the reaction.
(D) Mn²⁺ acts as auto-catalyst.
Answer:
(D) Mn²⁺ acts as auto-catalyst.

Explanation:
When KMnO₄ solution is added to oxalic acid solution, the decolourisation is slow in the beginning but becomes instantaneous after sometime because Mn acts as an auto-catalyst. Reduction half-reaction:
[MnO^–₄ + 8H⁺ + 5e^– → Mn²⁺ + 4H₂O] x 2

Oxidation half-reaction:
[C₂O^–₄ → 2CO₂ + 2e^–] x 5

Overall equation:
2MnO^–₄ + 16H⁺ + 5C₂O^2-₄ → 2Mn²⁺ + 10CO₂ + 8H₂O
End point of this reaction: Colourless to light pink.

d And f Block MCQ Chapter 8 Class 12 Question 4.

The oxidation state of Ni in [Ni(CO)₄] is

(A) 0
(B) 2
(C) 3
(D) 4
Answer:
(A) 0

Explanation:
I.ct oxidation stale of Ni = x
x + 0 = 0 (CO is neutral ligand)
x = 0

MCQ Of d And f Block Elements Chapter 8 Question 5.

Which of the following is the reason for Zinc not exhibiting variable oxidation state ?

(A) inert pair effect
(B) completely filled 3d subshell
(C) completely filled 4s subshell
(D) common ion effect
Answer:
(B) completely filled 3d subshell

Explanation:
Zinc doc- not exhibit a variable oxidation state as it has completely filled 3d subshell.
Zn → [Ar] 3d¹⁰ 4s² (Atomic number 30)

d And f Block Elements MCQ Pdf Chapter 8 Question 6.

Which of the following is a diamagnetic ion ? (Atomic numbers of Sc, V, Mn and Cu are 21, 23,25 and 29 respectively)

(A) V²⁺
(B) Sc³⁺
(C) Cu²⁺
(D) Mn³⁺
Answer:
(B) Sc³⁺

Explanation:
SC³⁺ is a diamagnetic ion. Atomic number is 21.
[Ar]3d⁰ is Sc³⁺ electronic configuration. Since its d subshell is empty it is diamagnetic as it has noble gas configuration. :

d Block MCQ Class 12 Chapter 8 Question 7.

Which set of ions exhibit specific colours? (Atomic number of Sc = 21, Ti = 22, V=23, Mn = 25, Fe = 26, Ni = 28 Cu = 29 and Zn =30)

(A) Sc³⁺, Ti⁴⁺, Mn³⁺
(B) Sc³⁺, Zn²⁺, Ni²⁺
(C) V ³⁺, V²⁺, Fe³⁺
(D)Ti³⁺,Ti⁴⁺,Ni²⁺

Answer:
(C) V ³⁺, V²⁺, Fe³⁺

Explanation:
V ³⁺, V²⁺, Fe³⁺ ions exhibit specific colours.

Atomic number of V = 23,
Electronic configuration of V – [Ar]3d³ 4s²
Electronic configuration of V2t – |Ar]3d³
Electronic configuration of V3+ – [Ar] 3d²

Atomic number of Fe = 26
Electronic configuration of Fe – [Ar]3d⁶ 4s²
Electronic configuration of Fe³⁺ – [Ar]⁶d⁵
Since these ions have partially filled d- subshells, they exhibit colour. Most transition-metal ions have a partially filled d subshell.
As for other ions,

Atomic number of Sc = 21
Electronic configuration of Sc – [Ar]3d 4s²
Electronic configuration of Sc³⁺ – [Ar]3d¹⁰
Since d subshell is empty, it shows no colour.

Atomic number of Ti = 22
Electronic configuration of Ti- [Ar]3d² 4s²
Electronic configuration of Ti⁴⁺ – [Ar]3d⁰
Since d subshell is empty, it shows no colour.

Atomic number of Mn = 25
Electronic configuration of Mn- [Ar]Sd³ 4s²Electronic configuration of Mn²⁺ [Ar]3d⁵ Since d subshell is partially filled, it shows colour.

Atomic number of Ni = 28
Electronic configuration of Ni- [Ar]3d⁸ 4s²
Electronic configuration of Ni²⁺ [Ar]3d⁸
Since d subshell is partially filled, it shows colour.

Atomic number of Zn =30
Electronic configuration of Zn – [Ar]3d¹⁰ 4s²
Electronic configuration of Zn²⁺ – [Ar]3d¹⁰
Since d subshell is full, it shows no colour.

d Block Elements MCQ Questions Chapter 8 Question 8.

Which of the following oxidation state is common for all lanthanoids?

(A) +2
(B) +3
(C) +4
(D) +5
Answer:
(B) +3

Explanation:
Most common oxidation state fori lanthanoids is +3.

MCQ Questions On d And f Block Elements Question 9.

There are 14 elements in actinoid series. Which of the following element does not belong to this series?

(A) U
(B) Np
(C) Tm
(D) Fm
Answer:
(C) Tm

Explanation:
Tm (Thulium) is a lanthanoid.

MCQs On d And f Block Elements Chapter 8 Question 10.

Gadolinium belongs to 4f series. Its atomic number is 64. Which of the following is the correct electronic configuration of Gadolinium?

(A) [Xe]4f⁷5d¹6s²
(B) [Xe] 4f⁶5d²6s²
(C) [Xe] 4f⁸6d²
(D) [Xe] 4f⁹5s¹
Answer:
(A) [Xe]4f⁷5d¹6s²

Explanation:
64Gd : [Xe] 4f⁷ 5d¹ 6s²

d Block Elements MCQ Chapter 8 Question 11.

Interstitial compounds are formed when small atoms are trapped inside the crystal lattice of metals. Which of the following is not the characteristic property of interstitial compounds?

(A) They have high melting points in comparison to pure metals.
(B) They are very hard.
(C) They retain metallic conductivity.
(D) They are chemically very reactive.
Answer:
(D) They are chemically very reactive.

Explanation:
Interstitial compounds are chemically inert.

Class 12 Chemistry Chapter 8 MCQ Question 12.

Which of the following statements is not correct?

(A) La is actually transition element.
(B) In Lanthanide series, Ionic radii decrease from La3+ toLu3+.
(C) La(OH)₃ is less basic than Lu(OH)₃
(D) Ionic radii of Zr and Hf are almost similar due to Lanthanoid contraction.
Answer:
(C) La(OH)₃ is less basic than Lu(OH)₃

Explanation:
La(OH)₃ is more basic than Lu(OH)₃. It is because of the fact that Due to lanthanoid contraction the size of lanthanoid ion decreases regularly with increase in atomic size. Thus covalent character between lanthanoid ion and OH^– increases from La³⁺ to Lu³⁺. Thus the basic character of hydroxides decreases from La(OH)₃ to Lu(OH)₃.

Class 12 Chemistry d And f Block Elements MCQ Question 13.

Lanthanoid contraction is caused due to –

(A) Atomic number
(B) Size of 4f orbitals
(C) Effective nuclear charge
(D) Poor shielding effect of 4f electrons
Answer:
(D) Poor shielding effect of 4f electrons

Explanation:
The Lmlhanoid contraction is due to poor shielding effect of 4f electrons.

d And f Block Elements Class 12 MCQs Chapter 8 Question 14.

In which of the following elements, 5f orbitals are progressively filled?

(A) Alkaline earth metals
(B) Actinoids
(C) Lanthanoids
(D) Transition elements
Answer:
(B) Actinoids

Explanation:
Actinoids are 5f block elements so in actinoids, 5f orbitals are progressively filled.

Assertion And Reason Based MCQs

Directions: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
(A) Both A and R are true and R is the correct explanation of A.
(B) Both A and R are true but R is NOT the correct explanation of A.
(C) A is true but R is false.
(D) A is false and R is True.

MCQ On d Block Elements Class 12 Chapter 8 Question 1.

Assertion (A): Cu²⁺iodide is not known.
Reason (R): Cu²⁺ oxidises I^– to iodine.

Answer:
(A) Both A and R are true and R is the correct explanation of A.

Explanation:
Cu²⁺ oxidises iodide to iodine hence cupric iodide is converted to cuprous iodide.

MCQ On d And f Block Elements Class 12 Chapter 8 Question 2.

Assertion (A): The highest oxidation state of osmium is +8.
Reason (R): Osmium is a 5d-block element.

Answer:
(B) Both A and R are true but R is NOT the correct explanation of A.

Explanation:
The highest oxidation state of osmium (Os) is 18. It is due to its ability to expand octet by using its all 8 electrons.

d-Block Elements MCQs With Answers Chapter 8 Question 3.

Assertion (A): Separation of Zr and Hf is difficult.
Reason (R): Because Zr and Hf lie in the same group of the periodic table.

Answer:
(B) Both A and R are true but R is NOT the correct explanation of A.

Explanation:
Separation of Zr and Hf is difficult as both have same size.

f Block Elements MCQs With Answers Chapter 8 Question 4.

Assertion (A): Cu cannot liberate hydrogen from adds.
Reason (R): Because it has positive electrode potential.

Answer:
(A) Both A and R are true and R is the correct explanation of A.

Explanation:
Copper (Cu) does not liberate hydrogen from acids due to the presence of positive electrode potential.

MCQ Of d Block Elements Class 12 Question 5.

Assertion (A): Transition metals have low melting points.
Reason (R): The involvement of greater number of (n – 1 )d and ns electrons in the interatomic metallic bonding.

Answer:
(D) A is false and R is True.

Explanation:
Transition melels have high melting points because of the involvement of greater number of (π – 1) and us electrons in the interatomic metallic bonding.

Question 6.

Assertion (A): Transition metals have high melting point.
Reason (R): Transition metals have completely filled d-orbitals.

Answer:
(C) A is true but R is false.

Explanation:
Transition metals have high melting points because of the involvement ot greater number of (π – 1)i1 and ns electrons in the interatomic metallic bonding.

Question 7.

Assertion: Separation of Zr and Hf is difficult.
Reason: Because Zr and Hf lie in the same group of the periodic table.

Answer:
(B) Both A and R are true but R is NOT the correct explanation of A.

Explanation:
Separation of Zr and Hf is difficult as both have same size.

Question 8.

Assertion (A): Chromium is an actinoid.
Reason (R): In Chromium, 3d orbitals are filled.

Answer:
(D) A is false and R is True.

Explanation:
Chromium is a transition element and it belongs to 3d series because in chromium, 3d orbitals are filled.

Question 9.

Assertion (A): Chemistry of Actinoids is more complicated than Lanthanoids.
Reason (R): Actinoid elements are radioactive in nature.

Answer:
(A) Both A and R are true and R is the correct explanation of A.

Explanation:
Chemistry of actinoids is more complicated than l anthanoids because actinoids are radioactive elements having relati\ ely short half-lives.

Question 10.

Assertion (A): Cerium (Ce) exhibits +4 oxidation state.
Reason (R): Ce⁴⁺ has 4f⁴ electronic configuration which is less stable.

Answer:
(C) A is true but R is false.

Explanation:
Cerium exhibits 4+ oxidation state because Ce⁴⁺ has 4f⁰ electronic configuration which is most stable.

Case-Based MCQs

I. Read the passage given below and answer the following questions:
Within the 3d series, manganese exhibits oxidation states in aqueous solution from +2 to +7, ranging from Mn²⁺(aq) to MnO^– (aq). Likewise, iron forms both Fe²⁺(aq) and Fe³⁺(aq) as well as the FeO^2- ion. Cr and Mn form oxyions CrO^2-₄, MnO^–₄, owing to their willingness to form multiple bonds. The pattern with the early transition metals – in the 3d series up to Mn, and for the 4d, 5d metals up to Ru and Os – is that the maximum oxidation state corresponds to the number of “outer shell” electrons.

The highest oxidation states of the 3d metals may depend upon complex formation (e.g., the stabilization of CO³⁺ by ammonia) or upon the pH (thus Mn0^2-₄ (aq) is prone to disproportionation in acidic solution). Within the 3d series, there is considerable variation in relative stability of oxidation states, sometimes on moving from one metal to a neighbour; thus, for iron, Fe³⁺ is more stable than Fe²⁺, especially in alkaline conditions, while the reverse is true for cobalt. The ability of transition metals to exhibit a wide range of oxidation states is marked with metals such as vanadium, where the standard potentials can be rather small, making a switch between states relatively easy.

In the following questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices on the basis of the above passage.
(A) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(B) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(C) Assertion is correct statement but reason is wrong statement.
(D) Assertion is wrong statement but reason is correct statement.

Question 1.

Assertion (A): Highest oxidation state is exhibited by transition metal lying in the middle of the series.
Reason (R): The highest oxidation state exhibited corresponds to number of (n-1)d electrons.

Answer:
(C) Assertion is correct statement but reason is wrong statement.

Question 2.

Assertion (A): Fe³⁺ is more stable than Fe²⁺.
Reason (R): Fe³⁺ has 3d⁵configuration while Fe²⁺ has 3d⁶ configuration.

Answer:
(A) Assertion and reason both are correct statements and reason is correct explanation for assertion.

Question 3.

Assertion (A): Vanadium had the ability to exhibit a wide range of oxidation states.
Reason (R): The standard potentials Vanadium are rather small, making a switch between oxidation states relatively easy.

Answer:
(A) Assertion and reason both are correct statements and reason is correct explanation for assertion.

Question 4.

Assertion (A): Transition metals like Fe, Cr and Mn form oxyions.
Reason (R): Oxygen is highly electronegative and has a tendency to form multiple bonds.

Answer:
(B) Assertion and reason both are correct statements but reason is not correct explanation for assertion.

Question 5.

Assertion (A): The highest oxidation states of the 3d metals depends only on electronic configuration of the metal.
Reason (R): The number of electrons in the (n-1) d and ns subshells determine the oxidation states exhibited by the metal.

Answer:
(D) Assertion is wrong statement but reason is correct statement.

II. Read the passage given below and answer the following questions:
The transition metals when exposed to oxygen at low and intermediate temperatures form thin, protective oxide films of up to some thousands of Angstroms in thickness. Transition metal oxides lie between the extremes of ionic and covalent binary compounds formed by elements from the left or right side of the periodic table. They range from metallic to semiconducting and deviate by both large and small degrees from stoichiometry.

Since d-electron bonding levels are involved, the cations-exist in various valence states and hence give rise to a large number of oxides. The crystal structures are often classified by considering a cubic or hexagonal close-packed lattice of one set of ions with the other set of ions filling the octahedral or tetrahedral interstices.

The actual oxide structures, however, generally show departures from such regular arrays due in part to distortions caused by packing of ions of different size and to ligand field effects. These distortions depend not only on the number of d-electrons but also on the valence and the position of the transition metal in a period or group.

In the following questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices on the basis of the above passage.
(A) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(B) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(C) Assertion is correct statement but reason is wrong statement.
(D) Assertion is wrong statement but reason is correct statement.

Question 1.

Assertion (A): Cations of transition elements occur in various valence states
Reason (R): Large number of oxides of transition elements are possible.

Answer:
(A) Assertion and reason both are correct statements and reason is correct explanation for assertion

Question 2.

Assertion (A): Crystal structure of oxides of transition metals often show defects.
Reason (R): Ligand field effect cause distortions in crystal structures.

Answer:
(A) Assertion and reason both are correct statements and reason is correct explanation for assertion

Question 3.

Assertion (A): Transition metals form protective oxide films.
Reason (R): Oxides of transition metals are always stoichiometric.

Answer:
(C) Assertion is correct statement but reason is wrong statement.

Question 4.

Assertion (A): CrO crystallises in a hexagonal close- packed array of oxide ions with two out of every three octahedral holes occupied by chromium ions.
Reason (R): Transition metal oxide may be hexagonal close-packed lattice of oxide ions with metal ions filling the octahedral voids.

Answer:
(D) Assertion is wrong statement but reason is correct statement.

III. Read the passage given below and answer the following questions:
The d block elements are the 40 elements contained in the four rows of ten columns (3 – 12) in the periodic table. As all the d block elements are metallic, the term d-block metals is synonymous. This set of d-block elements is also often identified as the transition metals, but sometimes the group 12 elements (zinc, cadmium, mercury) are excluded from the transition metals as the transition elements are defined as those with partly filled d or f shells in their compounds. Inclusion of the elements zinc, cadmium and mercury is necessary as some properties of the group 12 elements are appropriate logically to include with a discussion of transition metal chemistry.

The term transition element or transition metal appeared to derive from early studies of periodicity such as the Mendeleev periodic table of the elements. His horizontal table of the elements was an attempt to group the elements together so that the chemistry of elements might be explained and predicted.

In this table there are eight groups labeled I – VIII with each subdivided into A and B subgroups. Mendeleev recognized that certain properties of elements in Group VHI are related to those of some of the elements in Group VII and those at the start of the next row Group I. In that sense, these elements might be described as possessing properties transitional from one row of the table to the next.

In the following questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices on the basis of the above passage.

(A) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(B) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(C) Assertion is correct statement but reason is wrong statement.
(D) Assertion is wrong statement but reason is correct statement.

Question 1.

Assertion (A): Group 12 elements are not considered as transition metals.
Reason (R): Transition metals are those which have incompletely filled d shell in their compounds.

Answer:
(A) Assertion and reason both are correct statements and reason is correct explanation for assertion.

Question 2.

Assertion (A): All d block elements are metallic in nature.
Reason (R): The d – block elements belong to Group 3 – 12 of the periodic table.

Answer:
(B) Assertion and reason both are correct statements but reason is not correct explanation for assertion.

Question 3.

Assertion (A): Group VII elements of Mendeleev periodic table are transition elements.
Reason (R): Group I -VIII in Mendeleev periodic table is divided into two subgroups, A and B.

Answer:
(D) Assertion is wrong statement but reason is correct statement.

Question 4.

Assertion (A): Nickel is a transition element that belongs to group 10 and period 4 of the modern periodic table.
Reason (R): Electronic configuration of Nickel is [Ar]₁₈ 3d⁸ 4s²

Answer:
(A) Assertion and reason both are correct statements and reason is correct explanation for assertion.

IV. Read the passage given below and answer the following questions:
In transition elements, generally, ions of the same ‘ charge in a given series show progressive decrease in-radius with increasing atomic number. This is because the new electron enters a d orbital each time the nuclear charge increases by unity. But the radii of the third (5d) series are virtually the same as those of the corresponding members of the second series. This phenomenon is associated with the intervention of the 4f orbitals which must be filled before the 5d series of elements begin. The filling of 4f before 5d orbital results in a regular decrease in atomic radii called Lanthanoid contraction.

In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
(A) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(B) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(C) Assertion is correct statement but reason is wrong statement.
(D) Assertion is wrong statement but reason is correct statement.

Following are the transition metal ions of 3d series: Ti⁴⁺, V²⁺, Mn³⁺, Cr³⁺ (Atomic number: Ti = 22, V = 23, Mn = 25, Cr = 24)

Question 1.

Assertion (A): Among the given ions, Cr³⁺ is the most stable in an aqueous environment.
Reason (R): Cr³⁺ has half filled t³2g.

Answer:
(D) Assertion is wrong statement but reason is correct statement.

Explanation:
Cr³⁺, half filled t³2g.

Question 2.

Assertion (A): Among the given ions, Mn³⁺ is the most strong oxidizing agent.
Reason (R): Mn³⁺ has an unstable configuration.

Answer:
(C) Assertion is correct statement but reason is wrong statement.

Explanation:
Mn³⁺ is the strong oxidising agent because it has 4 electrons in its valence shell and when it gains one electron than it forms Mn²⁺, it results in the half-filled (d⁵) configuration that provides extra stability.

Question 3.

Assertion (A): Ti4+ ion is colourless.
Reason (R): All valence electrons are unpaired in Ti⁴⁺ ion.

Answer:
(A) Assertion and reason both are correct statements and reason is correct explanation for assertion.

Explanation:
Ti⁴⁺, No unpaired electrons.

V. Read the passage given below and answer the following questions:
Although actinoids are similar to lanthanoids in that their electrons fill the 5f orbitals in order, their chemical properties are not uniform and each element has characteristic properties. Promotion of 5f – 6d electrons does not require a large amount of energy and examples of compounds with ππ – acid ligands are known in which all the 5f, 6d, 7s, and 7p orbitals participate in bonding. Trivalent compounds are the most common, but other oxidation states are not uncommon. Especially thorium, protactinium, uranium, and neptunium tend to assume the +4 or higher oxidation state. The following questions are multiple choice questions. Choose the most appropriate answer:

Question 1.

Which of the following oxidation state is common for all lanthanoids?

(A) +2
(B) +3
(C) +4
(D) +5
Answer:
(B) +3

Explanation:
All of the lanthanide elements are 5 commonly known to have the +3 oxidation stale,

Question 2.

There are 14 elements in actinoid series. Which of the following element does not belong to this series?

(A) U
(B) Np
(C) Tm
(D) Fm
Answer:
(C) Tm

Explanation:
Tm is Thulium which belongs to Lanthanoids: Uranium(U), Neptunium(Np), Fermium(Fm) belong to Actinoid series.

Question 3.

General electronic configuration of actinoids is (n – 2)f^{1 – 14} (n – l)d^{0 – 2} ns² . Which of the following actinoids have one electron in 6d orbital?

(A) U (Atomic no. 92)
(B) Np (Atomic no.93)
(C) Pu (Atomic no. 94)
(D) Bk (Atomic no. 97)
Answer:
(A) U (Atomic no. 92)

Explanation:
Uranium has an electronic configuration of 5f 6d1 7s2.

Question 4.

Gadolinium belongs to 4f series. Its atomic number is 64. Which of the following is the correct electronic configuration of Gadolinium?

(A) [Xe]4f⁷5d¹6s²
(B) [Xe] 4f⁶5d²6s²
(C) [Xe]4f⁸6d²
(D) [Xe] 4f⁹5S¹
Answer:
(A) [Xe]4f⁷5d¹6s²

Explanation:
Gadolinium has an electronic configuration of [Xe]4f⁸6d²

MCQ Questions for Class 12 Chemistry with Answers