86. The crystal structure in most of the common metals is:

1. 1. cubic

   
   
   

   2. rhombohedral

   
   
   

   3. tetragonal

   
   
   

   4. triclinic

   
   
   

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1. View Hint View Answer Discuss in Forum

   The crystal structure in most of the common metals is cubic.

   Correct Option: A

   The crystal structure in most of the common metals is cubic.

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87. At 0 K, an extrinsic semiconductor behaves like a:

1. 1. perfect insulator

   
   
   

   2. good conductor

   
   
   

   3. superconductor

   
   
   

   4. metal

   
   
   

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1. View Hint View Answer Discuss in Forum

   At 0 K, an extrinsic semiconductor behaves like a perfect insulator.

   Correct Option: A

   At 0 K, an extrinsic semiconductor behaves like a perfect insulator.

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88. A material having different properties in different directions is known as:

1. 1. isotropic

   
   
   

   2. anisotropic

   
   
   

   3. crystalline

   
   
   

   4. metal

   
   
   

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1. View Hint View Answer Discuss in Forum

   A material having different properties in different directions is known as anisotropic.

   Correct Option: B

   A material having different properties in different directions is known as anisotropic.

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89. Two important semiconductors Ge and Si have:

1. 1. 4 valence electrons

   
   
   

   2. 3 valence electrons

   
   
   

   3. 1 valence electron

   
   
   

   4. 5 valence electrons

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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90. The interplanar distance in a cubic crystal is equal to the length of the cube. Miller indices of the related plane will be:

1. 1. (100)

   
   
   

   2. (110)

   
   
   

   3. 
      (10 1)

   
   
   

   4. (200)

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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