Periodic Properties and Chemical Bonding — DU B.Sc. (Prog.) Applied Physical Sciences with Industrial Chemistry Previous Year Question Papers

5. Write short notes on any three of the following: (a) LCAO method in MO approach (b) Metallic bonding (c) Catalytic properties of metals and their compounds 6. (a) What is s-p mixing? How can it be used for explaining magnetic behaviour of C,? Explain it using MO diagram of C,. (b) The electron gain enthalpy increases from B to C but it decreases from C to N. (c) Arrange the chlorides of the alkali metals in increasing order of solubility in water and explain it. (d) The 2nd ionisation enthalpies of alkali metals are higher than those of alkaline earth metals in respective periods. Explain. Chemical Bonding Science/Industrial Chemistry/Analytical 1. (a) State and explain Fajan's Rules with examples. (b) The cationic sizes are smaller whereas the anionic sizes are larger than respective atomic sizes. Explain with examples. (c) CO, is linear whereas SO,, is not. Explain. (d) Write limitations of VBT. 2. (a) Deduce the structures and shapes of following molecules based on VSEPR theory: 5+5+5=15 (b) Which of NO and NO* is more stable. Explain with MO diagrams. (c) Explain resonance, resonating structures, resonance hybrid and resonance energy. Draw all possible resonating structures of 3. (a) Define the term dipole moment. What is its common unit? Write its value in SI unit. Calculate percentage ionic character in a molecule AB if its dipole moment is 1.03 D and internuclear distance is 127 pm. (b) Draw MO diagram of CO. Explain its magnetic behavior and bond order. (c) Most of the transition metal compounds are paramagnetic and colored. Explain with examples. 4. (a) Draw the born-Haber cycle of NaBr. Calculate the enthalpy of formation of NaBr using Born-Haber cycle with following data: Lattice energy of NaBr, Uo = -718.8 kJmol-1 Enthalpy of atomisation of sodium, AHA(Na) =+107 kJ moll Enthalpy of atomisation of chlorine, First ionisation enthalpy of sodium, ! Electron affinity of bromine, AHEA(Br) = -324 (b Explain the following: (i) KI is soluble in alcohol whereas KCI is insoluble. (ii) HO is liquid whereas H,S is gas. (c) Explain the paramagnetic behavior of 0, using MO diagram. Also explain its bond order. 5+5+5=15