In Class 12 Boards there will be Case studies and Passage Based Questions will be asked, So practice these types of questions. Study Rate is always there to help you. Free PDF Download of CBSE Class 12 Chemistry Chapter 8 The d- and f-Block Elements Case Study and Passage Based Questions with Answers were Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Chemistry Case Study Questions The d- and f-Block Elements to know their preparation level.
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In CBSE Class 12 Chemistry Paper, There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.
The d- and f-Block Elements Case Study Questions With Answers
Here, we have provided case-based/passage-based questions for Class 12 Chemistry Chapter 8 The d- and f-Block Elements
Case Study/Passage-Based Questions
Case Study 1: The transition elements have incompletely filled d-subshells in their ground state or in any of their oxidation states. The transition elements occupy positions in-betweens- and p-blocks in groups 3-12 of the Periodic table. Starting from the fourth period, transition elements consist of four complete series: Sc to Zn, Y to Cd and La, Hf to Hg and Ac, Rf to Cn. In general, the electronic configuration of the outer orbitals of these elements is (n – 1)d1–10 ns0–2. The electronic configurations of outer orbitals of Zn, Cd, Hg, and Cn are represented by the general formula(n – 1)d10 ns2. All the transition elements have typical metallic properties such as high tensile strength, ductility, and malleability. Except for mercury, which is liquid at room temperature, other transition elements have typical metallic structures. The transition metals and their compounds also exhibit catalytic properties and paramagnetic behavior. Transition metal also forms alloys. An alloy is a blend of metals prepared by mixing the components. Alloys may be homogeneous solid solutions in which the atoms of one metal are distributed randomly among the atoms of the other.
Which of the following characteristics of transition metals is associated with higher catalytic activity?
(a) High enthalpy of atomization
(b) Variable oxidation states
(c) Paramagnetic behavior
(d) Colour of hydrated ions
Answer: (b) Variable oxidation states
Transition elements form alloys easily because they have
(a) same atomic number
(b) same electronic configuration
(c) nearly same atomic size
(d) same oxidation states.
Answer: (c) nearly same atomic size
The electronic configuration of tantalum (Ta) is
(a) [Xe]4f 05d16s2 (b) [Xe]4f 14 5d2 6s2
(c) [Xe]4f14 5d36s2 (d) [Xe]4f14 5d4 6s2
Answer: (c) [Xe]4f14 5d36s2
Which one of the following outer orbital configurations may exhibit the largest number of oxidation states?
(a) 3d54s1 (b) 3d54s2
(c) 3d24s2 (d) 3d34s2
Answer: (b) 3d54s2
The correct statement(s) among the following is/are
(i) all d- and f-block elements are metals
(ii) all d- and f-block elements form coloured ions
(iii) all d- and f-block elements are paramagnetic.
(a) (i) only (b) (i) and (ii) only
(c) (ii) and (iii) only (d) (i), (ii) and (iii)
Answer: (a) (i) only
Case Study/Passage-Based Questions
Case Study 2:Transition metal oxides are compounds formed by the reaction of metals with oxygen at high temperatures. The highest oxidation number in the oxides coincides with the group number. In vanadium, there is a gradual change from the basic V2O3 to less basic V2O4, and to amphoteric V2O5⋅ V2O4 dissolves in acids to give VO2+ salts. Transition metal oxides are commonly utilized for their catalytic activity and semiconductive properties. Transition metal oxides are also frequently used as pigments in paints and plastic. Most notably titanium dioxide. One of the earliest applications of transition metal oxides to the chemical industry involved the use of vanadium oxide for the catalytic oxidation of sulfur dioxide to sulphuric acid. Since then, many other applications have emerged, which include benzene oxidation to maleic anhydride on vanadium oxides; cyclohexane oxidation to adipic acid on cobalt oxides. An important property of the catalyst material used in these processes is the ability of transition metals to change their oxidation state under a given chemical potential of reductants and oxidants.
Which oxide of vanadium is most likely to be basic and ionic?
(a) VO (b) V2O3
(c) VO2 (d) V2O5
Answer: (a) VO
Vanadyl ion is
(a) VO2+ (b) VO2+
(c) V2O+ (d) VO43–
Answer: (a) VO2+
Which of the following statements is false?
(a) With fluorine vanadium can form VF5.
(b) With chlorine vanadium can form VCl5.
(c) Vanadium exhibits the highest oxidation state in oxohalides VOCl3, VOBr3 and fluoride VF5.
(d) With iodine vanadium cannot form VI5 due to oxidising power of V5+ and reducing nature of I–
Answer: (b) With chlorine vanadium can form VCl5.
The oxidation state of vanadium in V2O5 is
(a) +5/2 (b) +7
(c) +5 (d) +6
Answer: (c) +5
Identify the oxidizing agent in the following reaction.
(a) V2O5 (b) Ca
(c) V (d) None of these
Answer: (a) V2O5
Case Study 3: The unique behavior of Cu, having a positive Eo accounts for its inability to liberate H2 from acids. Only oxidizing acids (nitric and hot concentrated sulphuric acid) react with Cu, the acids being reduced. The stability of the half-filled (d5) subshell in Mn2+ and the completely filled (d10 ) configuration in Zn2+ are related to their Eo (M3+ /M2+) values. The low value for Sc reflects the stability of Sc3+ which has a noble gas configuration. The comparatively high value for Mn shows that Mn2+(d5) is particularly stable, whereas a comparatively low value for Fe shows the extra stability of Fe3+ (d5). The comparatively low value for V is related to the stability of V2+ (half-filled t2g level).
(i) Standard reduction electrode potential of Zn2+ /Zn is – 0.76 V. This means
(a) ZnO cannot be reduced to Zn by H2 under standard conditions |
(b) Zn cannot liberate H2 with concentrated acids |
(c) Zn is generally the anode in an electrochemical cell |
(d) Zn is generally the cathode in an electrochemical cell. |
Answer: (a) ZnO cannot be reduced to Zn by H2 under standard conditions
(ii) Eo values for the couples Cr3+/Cr2+ and Mn3+ /Mn2+ are -0.41 and +1.51 volts respectively. These values suggest that
c |
(b) Cr2+ is more stable than Cr3+ state |
(c) Mn3+ is more stable than Mn2+ |
(d) Cr2+ acts as an oxidizing agent whereas Mn3+ acts as a reducing agent |
Answer: (a) ZnO cannot be reduced to Zn by H2 under standard conditions
(iii) The reduction potential values of M, Nand O are +2.46, -1.13 and -3.13 Y respectively. Which of the following order is correct regarding their reducing property?
(a) O>N>M | (b) O>M>N | (c) M>N>O | (d) M>O>N |
Answer: (a) O>N>M
(iv) Which of the following statements are true?
(a) Mn2+ compounds are more stable than Fe2+ towards oxidation to +3 state.
(b) Titanium and copper both in the first series of transition metals exhibits +1 oxidation state most frequently.
(c) Cu+ ion is stable in aqueous solutions.
(d) The E0 value for the Mn3+ /Mn2+ couple is much more positive than that for Cr3+/Cr2+ or Fe3+/Fe2+.
(a) (b) and (c) | (b) (a) and (d) | (c) (a) and (c) | (d) (b) and (d) |
Answer: (b) (a) and (d)
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