Chemistry of d- and f-Block Elements and Quantitative Inorganic Analysis — DU B.Sc (hons) Chemistry Previous Year Question Papers

2. Attempt four questions in all. Explain the following by giving reasons. (a) Although gold and platinum have lower ionization enthalpy then 3d transition elements yet they are noble metals. Explain. (b) Lanthanoids show sharp bands in the adsorption spectra in contrast to transition elements. Explain (c) Why zinc, cadmium and mercury are not considered as a transition element. (d) The +3 oxidation state of Lanthanum (Z=57), Gadolinium (Z=64) and Lutetium (Z=71) are especially stable. Why? (e) Among TiC!, VCI, and FeCl,, which one will be drawn more strongly into the magnetic field and why. (3×5) 2. (a) Discuss the preparation, properties and structure of polyphosphonitrilic chloride molecule [NPC.,]3 (b) Explain silicon rubber. What are the chain building and chain stopping units in silicon? (c) Write the polymerization process for dialkyl dihydroxy silane. (d) What is the difference between co precipitation and post precipitation? 3. (a) Draw the structure of the following : (iii) Dimethyl silicon oil (b) Which is stronger base La(OH), or Lu(OH),. Why? (c) What is meant by heating to constant weight and why is it important? (d) Draw the plot for X Vs T (K) for ferromagnetic substance. (e) Magnetic susceptibility of ferromagnetic and antimagnetic can be calculated by. law. (5,2.5,2.5,2.5,2.5) 4. (a) Consider the Latimer Diagram for Mn in Acidic Medium. Answer the following questions : (i) Is there any tendency of Mn? to reduce to Mn? Give reasons. (ii) Calculate skip step EMF for MnO, to Mn?t, (iii) Which oxidation state of Mn are likely to disproportionate? (iv) Which is most stable species? (v) How is Latimer diagram different from Ebsworth? (b) Describe giving reason which one of the following part has the property indicated: (i) Crt or Fet (stronger reducing agent). (ii) Co't or Ni?+ (lower magnetic moment) (10,2.5x2) (a) Arrange the following monoxides of transition metal on the basis of decreasing basic character. (b) Actinides display a variety of oxidation states in comparison to that of lanthanides. Explain. (c) What is super saturation? How does the phenomenon of supersaturation affect the formation of particles in a solution? (d) Calculate the magnetic moment of Europium (III) (L=3). Explain the discrepancy between observed (3.4-3.6 BM) and calculated value of magnetic moment. (2.5,2.5,5,5) 6. Write a note on (Any Three) : (ii) Lanthanide contraction and its consequences. (iii) Separation of Lanthanides by cation exchange chromatography. (iv) Catalytic properties of transition element. (5x3)