Atomic Structure and Chemical Bonding (Inorganic Chemistry–I) — DU B.Sc (hons) Chemistry Previous Year Question Papers

(Inorganic Chemistry-I) 4. The questions should be numbered in accordance with the number in the question paper. 1. Explain any five of the following giving reasons : (i) Ionic compounds are hard but brittle. (i) NC1, does not exist whereas PCI, does. (iii) The first ionization enthalpy of Lithium is less than that of Ben Ilium but reverse is true for the second ionization enthalpy of Li. (iv) Half-filled and completely filled orbitals are more stable. (vi) NaCl is soluble in water but insoluble in CCI (5x3) 2. (a) State the limitations of Bohr's Model of an atom. What are the different types of quantum numbers? Give their significance. (b) Why is the atomic spectrum called the "fingerprint" of an element? In a hydrogen atom, an electron moves from the fifth to the second orbit. Calculate the wavelength of the corresponding spectral line. To which series of lines in the hydrogen spectrum does this spectral line belong, and in which region of the electromagnetic spectrum will it be observed? (c) Explain the following : (i) The electron gain enthalpy values of noble gases are taken to be zero. (ii) The ionization energy of O is less than that of N. (5,5,5) 3. (a) Discuss the significance of Heisenberg's Uncertainty Principle for macro and microscopic particles. The uncertainty in position of a moving bullet of mass 0.02 kg is 5.0 × 10-6 m. Calculate the uncertainty in its velocity. (h=6.626 × (b) Differentiate between the following : (i) Atomic orbital and molecular orbital (ii) Electron gain enthalpy and electronegativity (c) What is an angular wave function? Discuss its significance. Specify the quantum numbers) on which angular wave function depends. How many angular nodes are present in a 3p, orbital? (5,5,5) (a) Explain the geometry and shape of the following molecules using VSEPR (b) What is s-p mixing in Molecular Orbital Theory? Draw the MO diagram of C, molecule and explain its magnetic property and bond order. (C) What do you understand by radial probability? Draw the radial distribution function plots for the orbitals designated by the following quantum numbers: Indicate the number of radial nodes present in each case. (5,5,5) (a) Define dipole moment. Calculate percentage ionic character in HCI molecule if its dipole moment and inter nuclear distance is 1.03 D and 127 pm, respectively. (ID = 3.336 × 10-30 Cm, charge on one electron = 1.6 × 10-1°C). (b) What is Madelung's Constant? Explain, citing the example of NaCl. Write the Kapustinskii equation for lattice energy and give its advantages over Born-Lande equation. (c) List the salient features of Valence Bond Theory and discuss its limitations. 6. (a) Calculate the limiting radius ratio for octahedral geometry with coordination number 6. Discuss the limitations of radius ratio rules. (c) Draw the Born-Haber Cycle for NaCI, and calculate its enthalpy of formation using following data: Sublimation enthalpy of Na = 109 kJmol- Dissociation enthalpy of C1, = 243 kJmol-1