Q1. Answer in brief:

• i.) List the symmetries of the C6H6 molecule. (50 words)
• ii.) Draw the first Brillouin zone for a 2D oblique reciprocal lattice. (50 words)
• iii.) What are the advantages of the neutron diffraction method? (50 words)
• iv.) Write down the electronic configuration of the Si atom. What type of bonding would you expect to find in Si? (50 words)
• V.) The electronic and lattice heat capacities for copper at 0.01 K are 5.04×10-6 J/(kmole-K) and 4.60×10-11 J/(kmole-K) respectively. What do you conclude from these magnitudes? (50 words)
• vi.) Is the following statement true for vibrations of a chain of two different types of atoms: "At the centre of the Brillouin zone, the frequency of the optical branch is less than the frequency of the acoustic branch”? Explain. (50 words)
• vii.) The Fermi energy for silver is 5.48 eV. Which of the following is true : (a) the density of energy states is greater at 2 eV (b) the density of energy states is greater at 6 eV or (c) the density of energy states is same near both energies? (50 words)
• viii.) What is the probability that a donor atom at energy En is ionized ? (50 words)
• ix.) In which of the following ions do you expect angular momentum quenching and why: Ti³⁺, Gd³⁺, Ni²⁺ (50 words)
• x.) What is the function of the quartz crystal used in a digital watch? (50 words)