Main Group Chemistry — DU B.Sc. (Prog.) Applied Physical Science with Analytical Methods in Chemistry & Biochemistry Previous Year Question Papers

(b) Compare the structure, acidic strength, and thermal stability of oxoacids of sulphur: H2SO3 and H2SO4. Which one is a better oxidizing agent and why? (c) What are silicates? What is the basic structural unit of silicates? Give one example of a silicate mineral. 5+5+5 6. (a) Write short notes on the following: (i) lonie vs covalent nature H2O, H2S, (ii) Thermal stability trend in HF, HCI, (b) (i) Give one method of preparation of Caro's acid and explain its structure. (ii) Draw the structure of Marshall's acid. (c) What are cryptates? How do they differ from crown ethers in terms of structure and stability of their alkali metal complexes? Give two applications of cryptands. 1. (a) What are standard electrode potentials (SEP)? What are the categories in which metals are divided based on SEP? 5 2. (b) Discuss the structure and oxidation states of chlorine in its oxoacids: HOCl, HClO2, HClO3 and HClO4 .How does their thermal stability and oxidizing power vary with the number of oxygen atoms? 5 (c) Describe the Van Arkel-de Boer process and explain how it is used to obtain high-purity zirconium. 5 Write short notes on the following (any three) (a) Metallic character trend in s-block elements. (b) Alkali metal solutions in liquid ammonia. (c) Diagonal relationship in periodic table (d) Anomalous behavior of Lithium 3. (a) Write the chemical reaction for the preparation of borazine. Discuss its structure and highlight its similarities with benzene. 5 (b) Compare the structure and basicity of the follow in g ox oacid s: H 3PO3 (phosphorous acid), H 2SO4 and HClO4. 5 (c) Explain the zone refining process for the purification of germanium. 5 4. (a) Explain the structure and hydrolysis of P4O6 and P4O10. Why is P4O10 a good dehydrating agent? (b)(i) Write a note on the structure of oxyacids of sulphur. (ii) Write the general formula of ortho-, pyro- and cyclo- silicates. (c) (i) Discuss the acidic/basic nature, thermal stability, and hydrolysis products of the N2O5. (ii) Discuss the structure and acidic nature of any one oxide of sulphur. 5. (a) Explain the significance of an Ellingham diagram in metallurgy. Why do most Ellingham diagram lines have a positive slope?