Assignment Solid and Semiconductor 147 Ge Ge P Ge Ge Solid and Crystals 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 c b d 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 a Metals b Superconductors c Insulators d Semiconductors 6 The band gap in Germanium and silicon in eV respectively is a 0 7 1 1 b 1 1 0 7 c 1 1 0 d 0 1 1 AIEEE 2002 MP PMT 2001 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 conductor b P is n type semi conductor and Q is p type semi 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 insulatorsccEgEgEg conductorscinsulatorEgEgEg scinsulatorconductorEgEgEg insulatorconductorscEgEgEg 148 Solid and Semiconductor crystal maintained at grain boundries a A single representative unit spread out in whole of the material in ordered regular arrays gives a single b A polycrystal is compared of grains in which regular periodicity is broken inside the grains but regularity is 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 a Calcite b Quartz c Selenite d Tourmaline 13 The temperature coefficient of resistance of a conductor is 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 a 454 DCE 1997 b 908 15 At 0oK fermi level for metals a Separate empty and filled levels c Lies between empty levels 16 Which of the following statement is wrong b d c 602 d 802 Lies between filled levels Depends on metal MP PMT 1997 Pb CET 1998 AFMC 1998 RPET 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 X Y Z 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 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 b c d 22 Metallic solids are always opaque because AFMC 1994 Solid and Semiconductor 149 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 forms a Ionic bond b Vander Waal bond c Chemical bond d Covalent bond 26 Which of the following materials is non crystalline a Copper b Sodium chloride c Wood d Diamond CBSE 1993 CBSE 1993 27 The coordination number of 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 is NCERT 1982 a Fcc b Bcc c Both of the above d None of the above Semiconductor 31 A semiconductor is formed by 32 A hole carries a charge equal to a Co ordinate b Covalent bonds c Electro valent bonds d Metallic bonds MP PET 2004 MP PET PMT 2004 a Zero b Proton c Neutron d Electron 33 A piece of copper and another of germanium are cooled from room temperature to 77 K the resistance of MP PET 1999 AIEEE 2004 a Each of them increases b Each of them decreases c Copper decreases and germanium increases d Copper increases and germanium decreases 34 When germanium is doped with phosphorus the doped material has MP PMT 2004 a Excess positive charge b Excess negative charge cba cba cba cba 2COCuNaCl 150 Solid and Semiconductor c More negative current carriers carriers 35 Partially filled electron between forbidden gap is Bihar CECE 2004 a Conductor b Insulator c Semiconductor d All of the above 36 The temperature T dependence of resistivity of a semiconductor is represented by AIIMS 2004 d More positive current a P b P c P d P O …