CBSE Class 12 Chemistry D And F Block Elements Worksheet Set A

Question. 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

Question. The oxidation state of Ni in [Ni(CO)₄] is:
(A) 0
(B) 2
(C) 3
(D) 4
Answer : A

Question. The colour of a metal ion depends upon:
a. the nature of the ligand
b. the number of ligands
c. the shape of the complex
d. None of these
Answer : A, B, C

Question. Which of the following statements are correct regarding Mohr’s salt?
a. It does not dissolve in water completely
b. It is one of the primary standard substances used in the laboratory
c. The oxidation state of Fe in it is + III
d. It produces NH3 when NaOH is added into it
Answer : B, D

Question. K₂MnO₄ in unstable in solution and the green solution obtained is changed into purple colouration. Correct statements regarding the above change are.
a. It is disproportionation reaction
b. It produces KMnO₄
c. Overall solution becomes alkaline
d. It produces black precipitate of hydrated MnO₂
Answer : ALL

Question. When chromate is heated to Na₂CO₃ powder in the presence of air?
a. one gaseous product is formed
b. one product is water insoluble which is black brown in colour
c. one product is water soluble which is red in colour
d. one product is water soluble which is yellow in colour
Answer : A, B, D

Question. 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

Question. There are 14 elements in lanthanoid series. Which of the following element belong to this series?
(A) Ce
(B) Sm
(C) Tm
(D) All of the above
Answer : D

Question. Which of the following oxidation state is common for all lanthanoids?
(A) +2
(B) +3
(C) +4
(D) +5
Answer : B

Question. 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) V³⁺, V²⁺, Fe³⁺
(D) Ti³⁺, Ti⁴⁺, Ni²⁺
Answer : C

Question. Which of the following is the reason of Zinc for not exhibiting variable oxidation states ?
(A) Inert pair effect
(B) Completely filled 3d subshell
(C) Completely filled 4s subshell
(D) Common ion effect
Answer : B

Question. Which of the following statements is not correct?
(A) La is actually transition element.
(B) In Lanthanide series, ionic radii decrease from La³⁺ to Lu^3+.
(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

Question. 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

Question. 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

Question. 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

Question. In which of the following elements, 5f orbitals are progressively filled?
(a) Alkaline earth metals
(b) Actinoids
(c) Lanthanoids
(d) Transition elements
Answer : B

Question. Choose incorrect options from the following statements.
a. O₂ is evolved during the hydrolysis of XeF₂, XeF₄, XeF_{6 :}
b. K₂ Cr₂ O₇ is not a deliquescent substance
c. All C–C bonds are ruptured in glucose when it is treated with alkaline solution of AgNO₃
d. K₂ Cr₂ O₇ reacts with cold conc. H₂ SO₄ to produce a green compound
Answer : A, C

Question. 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

Question. Measurement of magnetic moment helps to predict?
a. whether the compound is paramagnetic or diamagnetic.
b. whether the compound is coloured or not.
c. the number of unpaired electrons in the system.
d. whether the compound is low spin of high spin, wherever it is applicable.
Answer : A, C, D

Question. Which of the following properties of a substance disappear in solution?
a. Paramagnetism
b. Diamagnetism
c. Ferromagnetism
d. Antiferromagnetism
Answer : C, D

Question. The colour of a compound may be due to:
a. polarization
b. d–d transition
c. f–f transition
d. charge transfer spectra
Answer : ALL

Question. For the standardization of hypo solution:
a. standard KMnO₄ can be used which is prepared fresh
b. standard K₂ Cr₂ O₇ can be used which is prepared one month before
c. Bothe can be used
d. None is suitable
Answer : A, B, C

Question. Consider the following reaction:

Then M is.
a. Au
b. Ag
c. Both
d. None
Answer : A, B, C

Assertion and Reason

Note: Read the Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:
a. If both assertion and reason are true and the reason is the correct explanation of the assertion.
b. If both assertion and reason are true but reason is not the correct explanation of the assertion.
c. If assertion is true but reason is false.
d. If the assertion and reason both are false.
e. If assertion is false but reason is true.

Question. Assertion: Rusting of an iron is an example of corrosion.
Reason: Rusting of iron is decreased by acids and electrolytes.
Answer : C

Question. Assertion: AgCl dissolves in NH₄OH solution.
Reason: Due to formation of a complex.
Answer : A

Question. Assertion: Tungsten filament is used in electric bulbs.
Reason: Tungsten is a metal of high melting point.
Answer : A

Question. Assertion: Magnetic moment values of actinides are lesser than the theoretically predicted values.
Reason: Actinide elements are strongly paramagnetic.
Answer : B

Question. Assertion: Pure iron is not used for making tools and machines.
Reason: Pure iron is hard.
Answer : C

Question. Assertion: Extraction of iron metal from iron oxide ore is carried out by heating with coke.
Reason: The reaction Fe₂ O₃ (s) → Fe(s) + (3/2) O₂ (g) is a spontaneous process.
Answer : D

Question. Assertion: AgBr is used in photography.
Reason: AgBr undergoes photochemical reaction.
Answer : B

Question. Assertion: The degree of complex formation in actinides  decreases in the order M⁴⁺ > MO²⁺₂ > M³⁺ MO⁺₂.
Reason: Actinides form complexes withπ -bonding ligands such as alkyl phosphines and thioethers.
Answer : B

Question. Assertion: The aqueous solution of FeCl₃ is basic in nature.
Reason: FeCl₃ hydrolyses in water.
Answer : E

Question. Assertion: Solution of Na₂CrO₄ in water is intensely coloured.
Reason: Oxidation state of Cr in Na₂CrO₄ is + VI.
Answer : A

Comprehension Based

Paragraph –I

A mixture is treated with KI as follows: 1 mole of each

Question. How many moles of are required the above process?
a. (1/2)mole
b. 2 moles
c. 1 mole
d. 1(1/2) moles
Answer : B

Question. How many moles of KI are consumed to obtain the product mixture?
a. 4 moles
b. 6(1/2)moles
c. 7 moles
d. 5(1/2)moles
Answer : A

Question. The precipitate obtained is:
a. CdI₂ + Cu₂ I₂
b. Cu₂ I₂
c. Cu₂ I₂ + FeI₂
d. None of these
Answer : B

Paragraph –II

Light green compound

(a) D and E are acidic gases.
(b) D is passed through HgCl₂ solution to give yellow precipitate.
(c) When E is passed through water first and then H₂S is passed, white turbidity is obtained
(d) A is water soluble and on addition of HgCl₂ in it, white precipitate is obtained which does not turn grey on addition of excess solution of A.

Question. D and E are respectively:
a. SO₂ and SO₃
b. SO₂ and SO₂
c. SO₂ and CO₂
d. CO₂ and CO
Answer : B

Question. They yellow precipitate in the above reaction is:
a. mercuric oxide
b. basic mercury (II) sulphite
c. basic mercury (II) sulphate
d. mercuric iodide
Answer : C

Question. C is soluble in:
a. dil. HCI
b. dil. H₂ SO₄
c. conc. H₂ SO₄ under hot conditions
d. boiled conc. HCI
Answer : D

Paragraph –III

Aqueous solution of 3A + AgNO₃ → Black ppt. (B).Aqueous

Question. The black precipitate is.
a. AgO
b. Ag₂O
c. Ag₂S
d. Ag
Answer : A

Question. The true oxidation state of Ag in the black precipitate is/are.
a. + 2
b. + 1 and + 3
c. + 1
d. None of these
Answer : B

Question. The formula of pink precipitate (E) is.
a. BaSO₄
b. Ba(MnO4)₂
c. MnO₂
d. MnSO₄ Integer
Answer : A

Integer

Question. The sum of the oxidation state of Mn in KMnO₄, K₂MnO₄ and K₃MnO₄ is:
Answer : 18

Question. The number of the following reagents that produce ppt. with ZnSO₄ solution is. NaOH, N₂ CO₃ , NaCl, Na₂ HPO₄ , Na₂ S, CH₃ CO₃ Na
Answer : 4

Question. The number of equivalent Cr–O bonds in CrO²⁻₄ is:
Answer : 4

Question. The highest oxidation state of Cr will be:
Answer : 6

Question. A transition element X has a configuration [Ar]3d⁴ in its +3 oxidation state. Its atomic number is:
Answer : 25

Question. The change in the magnetic moment value when [Cu (H₂ O)₄ ]²⁺ is converted to [Cu (H₃ O)₄ ]²⁺ is:
Answer : 0

Question. The change in the number of unpaired electrons when [Fe (H₂ O)₆ ]²⁺ is changed into  [Fe (CN)₆]⁴⁻ is:
Answer : 4

Question. In acidic medium one mole of MnO⁻₄ accepts how many moles of electrons in a redox process?
Answer : 5

Match the Column

Question. Match the names with their chemical formulae:
         Column I                            Column II
(A) Kipp’s apparatus                1. HgCl₂
(B) Corrosive sublimate          2. Cu (OH)₂ ⋅ 2CuCO₃
(C) Azurite                              3. FeSO₄ solution
(D) Bordeaux mixture             4. Ca(OH)₂ + CuSO₄
a. A→3, B→1, C→2, D→4
b. A→2, B→4, C→3, D→1
c. A→1, B→3, C→2, D→4
d. A→4, B→1, C→3, D→2
Answer : A

Question. Match the compounds with their chemical properties:
      Column I                         Column II
(A) KMnO₄                 1. Acts as oxidizing agent.
(B) K₂Cr₂O₇              2. All X–O bonds are equivalent.
(C) Na₂SO₄               3. d3shybridization for the central atom(s).
a. A→1,2,3; B→1,3; C→2
b. A→2; B→4; C→3
c. A→1; B→3; C→2
d. A→4; B→1; C→3
Answer : A

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, but (R) is true.

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

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

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

Question. Assertion (A): Cu cannot liberate hydrogen from acids.
Reason (R): Cu has positive electrode potential. 
Answer : A

Question. 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

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

Question. Assertion (A): Lanthanoids have poor tendency to form complexes.
Reason (R): Lanthanoids has low density. U
Answer : A

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

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 MnO₄^– (aq). Likewise, iron forms both Fe²⁺(aq) and Fe³⁺(aq) as well as the FeO₄²⁻₄ ion. Cr and Mn form oxoanions CrO²⁻₄, MnO₄⁻, 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 upto 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 stabilisation of Co³⁺ by ammonia) or upon the pH (thus MnO₄²⁻ (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. Assertion (A): Vanadium had the ability to exhibit a wide range of oxidation states.
Reason (R): The standard potentials of vanadium are rather small, making a switch between oxidation states relatively easy. 
Answer : A

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

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

Question. Assertion (A): Fe³⁺ is more stable than Fe²⁺.
Reason (R): Fe³⁺ has 3d5 configuration while Fe²⁺ has 3d6 configuration. 
Answer : A

Question. 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

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

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

Question. Assertion (A): CrO crystallises in a hexagonal closepacked 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

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

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 VIII 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. 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. R
Answer : D

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

Question. 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]3d⁸⁴s².
Answer : A

Question. 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

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. Assertion (A): There is irregular trend in ionization energy in the group of lanthanoid series.
Reason (R): Ionization energy in lanthanoid series vary due to lanthanoid contraction.
Answer : A

Question. Assertion (A): Among the given ions, Cr³⁺ is the most stable in an aqueous environment.
Reason (R): Cr³⁺ has half filled t_2g³.
Answer : A

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

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

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