STMARYTX PHYS 042 - Assignment- Solid and Crystals
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11-Solid and Semiconductor-Assignment.pdf (p.1-23)OO (1)P12-Solid & Semiconductors-Answersheet.pdf (p.24-25)Solid and Semiconductor 147 Ge P Ge Ge Ge Assignment 1. The manifestation of band structure in solids is due to [DCE 2000; AIEEE 2004] (a) Heisenberg's uncertainty principle (b) Pauli's exclusion principle (c) Bohr's correspondence principle (d) Boltzmann's law 2. For non-conductors, the energy gap is [Similar to (DPMT 1988); EAMCET (Engg.) 1995; MP PET 1996; RPET 2003] (a) 6 eV (b) 1.1 eV (c) 0.8 eV (d) 0.3 eV 3. Which is the correct relation for forbidden energy gap in conductor, semi-conductor and insulator [RPMT 2001; AIEEE 2002] (a) insulatorsccEgEgEg  (b) conductorscinsulatorEgEgEg  (c) scinsulatorconductorEgEgEg  (d) insulatorconductorscEgEgEg  4. The valence band and conduction band of a solid overlap at low temperature, the solid may be [Orissa JEE 2002] (a) A metal (b) A semiconductor (c) An insulator (d) None of these 5. The energy band gap is maximum in [AIEEE 2002] (a) Metals (b) Superconductors (c) Insulators (d) Semiconductors 6. The band gap in Germanium and silicon in eV respectively is [MP PMT 2001] (a) 0.7, 1.1 (b) 1.1, 0.7 (c) 1.1, 0 (d) 0, 1.1 7. Wires P and Q have the same resistance at ordinary (room) temperature. When heated, resistance of P increases and that of Q decreases. We conclude that [MP PMT 1995; MP PET 1995, 2001] (a) P and Q are conductors of different materials (b) P is n-type semi-conductor and Q is p-type semi-conductor (c) P is semi-conductor and Q is conductor (d) P is conductor and Q is semiconductor 8. The nature of binding for a crystal with alternate and evenly spaced positive and negative ions is [CBSE PMT 2000] (a) Covalent (b) Metallic (c) Dipolar (d) Ionic 9. If the distance between the conduction band and valence band is 1 eV, then this combination is [AIIMS 2000] (a) Metal (b) Insulator (c) Conductor (d) Semiconductor s 10. For a crystal system, a = b = c,  =  =   90o, the system is [BHU 2000] (a) Tetragonal system (b) Cubic system (c) Orthorhombic system (d) Rhombohedral system 11. Which of the following statements is wrong [BHU 2000] Solid and Crystals148 Solid and Semiconductor (a) A single representative unit spread out in whole of the material in ordered regular arrays gives a single crystal (b) A polycrystal is compared of grains in which regular periodicity is broken inside the grains but regularity is maintained at grain boundries (c) In an amorphous material each grain is composed of a single representative unit (d) In liquid crystals periodicity is maintained in only one or two dimensions. 12. Biaxial crystal among the following is [Pb CET 1998] (a) Calcite (b) Quartz (c) Selenite (d) Tourmaline 13. The temperature coefficient of resistance of a conductor is [AFMC 1998] (a) Positive always (b) Negative always (c) Zero (d) Infinite 14. Potassium has a bcc structure with nearest neighbour distance 4.525 A. Its molecular weight is 39. Its density in kg/m-3 is [DCE 1997] (a) 454 (b) 908 (c) 602 (d) 802 15. At 0oK, fermi level for metals [RPET 1997] (a) Separate, empty and filled levels (b) Lies between filled levels (c) Lies between empty levels (d) Depends on metal 16. Which of the following statement is wrong [MP PMT 1997] (a) Resistance of a semi-conductor decreases on increasing the temperature (b) Displacement of holes is opposite to the displacement of electrons in an electric field (c) Resistance of a good conductor decreases on increasing the temperature (d) N-type semiconductors are neutral 17. The expected energy of the electrons at absolute zero is called [RPET 1996] (a) Fermi energy (b) Emission energy (c) Work function (d) Potential energy 18. The energy band diagrams for three semiconductor samples of silicon are as shown. We can then assert that [Haryana CEE 1996] (a) Sample X is undoped while samples Y and Z have been doped with a third group and a fifth group impurity respectively (b) Sample X is undoped while both samples Y and Z have been doped with a fifth group impurity (c) Sample X has been doped with equal amounts of third and fifth group impurities while samples Y and Z are undoped (d) Sample X is undoped while samples Y and Z have been doped with a fifth group and a third group impurity respectively 19. In good conductors of electricity, the type of bonding that exists is [CBSE 1995] (a) Ionic (b) Vander Waals (c) Covalent (d) Metallic X Y ZSolid and Semiconductor 149 20. Bonding in a germanium crystal (semiconductor) is [CPMT 1986; KCET 1992; EAMCET (Med.) 1995] (a) Metallic (b) Ionic (c) Vander Waal’s type (d) Covalent 21. In a triclinic crystal system [EAMCET (Med.) 1995] (a) cba ,  (b) cba ,  (c) cba ,  (d) cba ,  22. Metallic solids are always opaque because [AFMC 1994] (a) Solids effect the incident light (b) Incident light is readily absorbed by the free electron in a metal (c) Incident light is scattered by solid molecules (d) Energy band traps the incident light 23. Forbiden energy gap in a pure conductor is [EAMCET (Med.) 1994] (a) 6 eV (b) 1.1 eV (c) 0.7 eV (d) 0 eV 24. In which of the following ionic bond is present [EAMCET (Med.) 1994] (a) NaCl (b) Ar (c) Si (d) Ge 25. Solid 2CO forms [CBSE 1993] (a) Ionic bond (b) Vander Waal bond (c) Chemical bond (d) Covalent bond 26. Which of the following materials is non crystalline [CBSE 1993] (a) Copper (b) Sodium chloride (c) Wood (d) Diamond 27. The coordination number of Cu is [AMU 1992] (a) 1 (b) 6 (c) 8 (d) 12 28. Which one of the following is the weakest kind of bonding in solids [CBSE PMT 1992; KCET 1992] (a) Ionic (b) Metallic (c) Vander Waals (d) Covalent 29. In a crystal, the atoms are located at the position of [AMU 1985] (a) Maximum potential energy (b) Minimum potential energy (c) Zero potential energy(d) Infinite potential energy 30. Crystal structure of NaCl is

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STMARYTX PHYS 042 - Assignment- Solid and Crystals

Course: Phys 042-
Pages: 25
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