CBSE Class 12 Chemistry The d and f Block Elements MCQs Set H

Question. The hybridization state of the Cu in the compound [Cu(NH₃)₄]SO₄ is
(a) sp³
(b) sp² d
(c) sp³ d ²
(d) dsp²   
Answer: d

Question. Manganese exhibits maximum oxidation state in:
(a) K₂MnO₄
(b) KMnO₄
(c) MnO₂
(d) Mn₃O₄
Answer: a

Question. The complex ion [Cu(NH3)4] ⁺² is
(a) tetrahedral and paramagnetic
(b) tetrahedral and diamagnetic
(c) square planar and paramagnetic
(d) square planar and diamagnetic 
Answer: c

Question. In an octahedral crystal field, the t_2g orbital are
(a) raised in energy by 0.4 Δo
(b) lowered in energy by 0.4 Δo
(c) raised in energy by 0.6 Δo 
(d) lowered in energy by 0.6 Δo   
Answer: b

Question. Which of the following is a complex of metal other than transition metal?
(a) Haemoglobin
(b) Chlorophyll
(c) Ferrocene
(d) Vitamin B12 
Answer: b

Question. The tetrahedral complexes are generally high spin. This is because
(a) Δt < P
(b) Δt > P
(c) Δt = P
(d) none of these 
Answer: a

Question.The primary and secondary valency of copper in the complex [Cu(NH₃)₄]SO₄ are
(a) 2, 4
(b) 4, 2
(c) 0, 4
(d) 1, 4 
Answer: a

Question. Which of the following is not a double salt but a coordinate compound?
(a) KCl.MgCl₂.6H₂O
(b) FeSO₄.(NH₄)₂SO₄.6H₂O
(c) K₂SO₄.Al₂(SO₄)₃.24H₂O
(d) 4KCN.Fe(CN)₂   
Answer: b

Question. If Δo < P, then the correct electronic configuration for d4 system will be
(a) t_2g ⁴ eg ⁰
(b) t_2g ³ eg ¹
(c) t_2g ⁰ eg ⁴
(d) t_2g ² eg ²   
Answer: b

Question. The hybrid state of Co in high spin complex, K₃[CoF₆] is
(a) sp³ d ²
(b) sp³
(c) d² sp³
(d) sp³ d 
Answer: a

Question. Which of the following is amphotric oxide?
Mn₂O₇, CrO₃, Cr₂O₃, CrO, V₂O₅, V₂O₄.
(a) V₂O₅, Cr₂O₃
(b) Mn₂O₇, CrO₃
(c) CrO, V₂O₅
(d) V₂O₅, V₂O₄
Answer: a

Question. The magnetic moment is associated with its spin angular momentum. Spin only magnetic moment value of Cr³⁺ ion is ………..
(a) 2.87 B.M
(b) 3.87 B.M
(c) 3.47 B.M
(d) 3.57 B.M
Answer: b

 Question. Which of the following ions show higher spin only magnetic moment value?
(a) Ti³⁺
(b) Mn²⁺
(c) Fe²⁺
(d) Co³⁺
Answer: b,c

Question. The equivalent wight of K₂Cr₂O₇ in acid medium is equal to
(a) molecule weight
(b) 1/2 molecular weight
(c) 1/6 molecular weight
(d) 1/5 molecular weight
Answer: c

Question. The equivalent weight of KMnO₄ (formula weight M) when it is used as an oxidant in neural medium is
(a) M
(b) M/2
(c) M/3
(d) M/5
Answer: d

Question. Which of the following statement is correct?
(a) [Cu(NH₃)₄] ²⁺ is diamagnetic while [Fe(CN)₆] ^4- is paramagnetic
(b) [Cu(NH₃)₄] ²⁺ is paramagnetic while [Fe(CN)₆] ^4- is diamagnetic
(c) both are paramagnetic
(d) both are diamagnetic 
Answer: b

Question. Which of the following will not act as oxidising agents?
(a) CrO₃
(b) MnO₃
(c) WO₃
(d) CrO₄^2–
Answer: b,c

Question. CrO₃ dissolves in aqueous NaOH to give:
(a) CrO₄^2–
(b) Cr(OH)₃
(c) Cr₂O₇^2–
(d) Cr(OH)₂
Answer: a

Question. Electronic configuration of a transition element in + 3 oxidation state is [Al] 3d⁵. What is is atomic number?
(a) 25
(b) 26
(c) 27
(d) 24
Answer: b

Question. One of the characteristics of transition metals to form the complex ion is:
(a) Having unpaired electron in d-subshell
(b) Having paired electrons in d-subshells
(c) Providing empty d-orbitals
(d) Having small charge/size ratio
Answer: d

Question. The electronic configuration of gadolinium (At. No 64) is:
(a) [Xe] 4f ⁸ 5d⁰ 6s²
(b) [Xe] 4f ⁷ 5d² 6s²
(c) [Xe] 4f ³ 5d⁵ 6s²
(d) [Xe] 4f ⁶ 5d² 6s²
Answer: b

Question. The correct electronic configuration of copper atom is:
(a) 3d¹⁰4s¹
(b) 3d¹⁰4s²
(c) 3d⁹4s²
(d) 3d⁵4s²4p⁴
Answer: b

Question. On addition of small amount of KMnO₄ to concentrated H₂SO₄, a green oily compound is obtained which is highly explosive in nature. Identify the compound from the following.
(a) Mn₂O₇
(b) MnO₂
(c) MnSO₄
(d) Mn₂O₃
Answer: a

Question. Which of the following oxidation state is common for all lanthanoids?
(a) + 2
(b) + 3
(c) + 4
(d) + 5
Answer: b

Question. KMnO₄ acts as an oxidising agent in acidic medium. The number of moles of KMnO₄ that will be needed to react with one mole of sulphide ions in acidic solution is:
(a) 25
(b) 35
(c) 45
(d) 15
Answer: a

Question. When KMnO₄ solution is added to oxalic acid solution, the decolourisation is slow in the beginning but becomes instantaneous after some time because:
(a) CO₂ is formed as the products
(b) Reaction is exothermic
(c) MnO₄ ^– catalysis the reaction
(d) Mn²⁺ acts as autocatalyst
Answer: d

Question. Transition elements show magnetic moment due to spin and orbital motion of electrons. Which of the following metallic ions have almost same spin only magnetic moment?
(a) CO²⁺
(b) Cr²⁺
(c) Mn²⁺
(d) Cr³⁺
Answer: a,c

Question. Generally transition elements and their salts are coloured due to the product of unpaired electrons in metal ions. Which of the following compounds are coloured?
(a) KMnO₄
(b) Ce(SO₄)₂
(c) TiCl₄
(d) Cu₂Cl₂
Answer: a,b

Question. Number of moles of K₂Cr₂O₇ reduced by one mole of Sn²⁺ ions is
(a) 1/3
(b) 3
(c) 1/6
(d) 6
Answer: c

Question. Which of the following actionoids show oxidation states upto + 7?
(a) Am
(b) Pu
(c) U
(d) Np
Answer: b,d

Question. Match the solutions given in Column 1 and the colours given in column II.
Column 1                               Column 2
(i) FeSO₄.7H₂O                    (a) green
(ii) NiCl₂.4H₂O                     (b) light pink
(iii) MnCl₂.4H₂O                   (c) Blue
(iv) COCl₂.6H₂O                  (d) Pale green
(v) Cu2Cl₂                            (e) pink
                                            (f) colourless
Answer: 
(i)—(d), (ii)—(a), (iii)—(b), (iv)—(e), (v)—(f)
 

Question. Match the components/elements given in column I with uses given in column II.
Column 1                                                   Column 2
(A) Lanthanoid oxide                                 (1) Production of iron alloy
(B) Lanthanoid                                          (2) Television screen
(C) Misch metal                                         (3) Petroleum cracking
(D) Magnesium based alloy                      (4) Lanthanoid metal + iron
(E) Mixed oxides of lanthanoids                (5) bullets
    are employed                                         
                                                                  (6) In X-ray screen
(a) A–4, B–3, C–1, D–2
(b) A–3, B–4, C–1, D–2
(c) A–4, B–1, C–2, D–3
(d) A–2, B–1, C–3, D–4
Answer: 
(i)—(b), (ii)—(a), (iii)—(d), (iv)—(e), (v)—(c)

Case Study Questions 

1.Pratham went to chemistry lab and he observed some pink, blue, green and yellow coloured solutions in la(b) His teacher explains that when an electron from lower energy d orbital is excited to higher energy d orbital (d-d transition),it absorbs light of visible range. The colour observed corresponds to the complementary colour of the light absorbe(d)

Question. Predict which of the following will be coloured in aqueous solution and why? Sc³⁺, Ti³⁺, V³⁺ , Cu⁺ , Fe³⁺
Answer. Ti³⁺, V³⁺ ,Fe³⁺ are coloured because they have unpaired d electrons which can undergo d-d transition.

Question. What is the colour of hydrated copper sulphate and why?
Answer. Hydrated CuSO₄ is blue in colour because of d-d transition.

Question. Explain why ZnSO₄ solution is colourless although it is a‘d’ block element?
Answer. Zn²⁺ ions have completely filled d10 electronic configuration.

Question. Which of the following is a coloured salt before heating ? (i) CuCO₃ (ii) PbCO₃ (iii) ZnCO₃ (iv) Na₂CO₃
Answer. CuCO₃

2. Pooja and Tanya were discussing about oxidation states .Pooja got confused about oxidation state of iron. Then Tanya explained to her that Transition metals show great variety of oxidation state in their compounds, e.g. Manganese exhibits all the oxidation states from +2 to +7. At the other end the only oxidation state of Zinc is +2 (no d electrons are involved).The maximum oxidation states of reasonable stability correspond in value to the sum of the s and d electrons up to manganese.

Question. Which of 3d series of transition metals exhibits the largest number of oxidation states and why?
Answer. Manganese exhibit the largest number of oxidation states. It shows the oxidation states +2, +3, +4, +5 ,+6, and + 7. The reason for that is the maximum number of unpaired electrons present in its outermost shell i.e. 3d⁵4s².

Question. Name a transition metal which doesn’t exhibit variable oxidation states.
Answer. Scandium (Z=21)

Question. What may be stable oxidation state of transition metal having 3d8 ground state electronic configuration?
Answer. +2

Question. Why Mn²⁺ compounds are more stable than Fe²⁺ towards oxidation to +3 states?
Answer. Since Mn²⁺ has stable half-filled electronic configuration, therefore Mn²⁺ compounds are more stable than Fe²⁺ towards oxidation to their +3 state. Fe²⁺(3d⁶) can lose one electron easily to give Fe³⁺(3d⁵, stable configuration).

Read the paragraph carefully and answer the Questions given below

The transition elements are those elements having a partially filled d subshell in any common oxidations state. The term “transition elements” most commonly refers to the d-block elements. The elements zinc , cadmium & mercury do not strictly meet the defining properties but are usually included with the transition elements because their similar properties. The general properties of transitions elements are o They are high melting point metals o They have several oxidation states o They usually from coloured compounds o They are often paramagnetic The transition elements include the important metals iron, copper and silver. Iron & titanium are the most abundant transition elements. Many catalysts for industrial reactions involve transition elements.

Question. Zn²⁺ salts are colourless due to
(a) d-d transition of electrons
(b) Fully filled d orbitals
(c) No d-d transition of electrons
(d) Fully filled d orbitals and no d-d transition of electrons   
Answer: d

Question. transition Metals are known to form complexes
(a) They have vacant d orbitals
(b) They hey high nuclear charge
(c) They can accept electrons from ligands
(d) All of above
Answer: d

Question. Iron is a transition element
(a) Iron has fully filled d orbitals
(b) Iron has partially filled d orbitals
(c) Iron has partially filled d subshell in metallic state
(d) None of Above. 
Answer: c

Question. Out of Sc³⁺,Cr³⁺,Zn²⁺,Mn²⁺which is highly paramagnetic
(a) Sc³⁺
(b) Cr³⁺
(c) Zn²⁺
(d) Mn²⁺   
Answer: d

Read the paragraph carefully and answer the Questions given below

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.

Coordination compounds are molecules that poses one or multiple metal centers that is bound to ligands (atoms, ions or molecules that donate electrons to the metal). Monodentate ligands donate one pair of electrons to the central metal atoms.
An example of these ligands are the halide ions (F-, Cl-, Br-, I-). Polydentate ligands, also called chelates or chelating agents, donate more than one pair of electrons to the metal atom forming a stronger bond and a more stable complex. A common chelating agent is ethylene diamine (en), which, as the name suggests, contains two ammines or :NH₂ sites which can bind to two sites on the central metal.

Question. Assertion: thiocyanate iron and isothiocyanate ions are ambidentate ligands
Reason : they have more than one donor atom which can coordinate.
Answer: a

Question. Assertion: bidentate, tridentate ligands form chelates.
Reason: they can donate more than two electron pairs to central atom and form a ring type of structure. 
Answer: a

Question. Assertion: the coordination number of Iron is six in Fe(CN)₆]^4-
Reason: cyanide is a bidentate ligand   
Answer: c

Question. Assertion: ethylenediamine is unidentate ligand
Reason: It forms stable complexes with metal
Answer: d

Note : In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choice.
(a) Both assertion and reason are True, and reason is the correct explanation of the assertion.
(b) Both assertion and reason are True, but reason is not the correct explanation of the assertion.
(c) Assertion is not True, but reason is True.
(d) Both assertion and reason are False.

Question. Assertion: Cu²⁺ iodide is not known. 
Reason: Cu²⁺ oxidises I– to iodine.

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