121. All of the following ceramic materials are isotropic except:

1. 1. SiO₄

   
   
   

   2. SiO₂

   
   
   

   3. MgSiO₃

   
   
   

   4. Al₂O₃

   
   
   

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   NA

   Correct Option: C

   NA

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122. For molybdenum, which has a body-centered cubic lattice structure, the number of atoms per unit cell is:

1. 1. 1

   
   
   

   2. 2

   
   
   

   3. 4

   
   
   

   4. 6

   
   
   

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   NA

   Correct Option: B

   NA

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123. Ferrites are:

1. 1. Ferromagnetic

   
   
   

   2. Ferrimagnetic

   
   
   

   3. Paramagnetic

   
   
   

   4. Antimagnetic

   
   
   

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   Ferrites are ferrimagnetic.

   Correct Option: B

   Ferrites are ferrimagnetic.

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124. Polythene is:

1. 1. a polymer of ethylene

   
   
   

   2. a vulcanised rubber

   
   
   

   3. impregnated cotton

   
   
   

   4. cellulose derivative

   
   
   

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   Polythene is a polymer of ethylene.

   Correct Option: A

   Polythene is a polymer of ethylene.

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125. Semiconductor A has a higher band gap than semiconductor B. If both A and B have the same dimensions, the same number of electrons at a given temperature and the same electron and hole mobilities, then:

1. 1. A has the same number of holes as B

   
   
   

   2. A has a larger number of holes than B

   
   
   

   3. A has less number of holes than B

   
   
   

   4. Any of the above statements (A), (B) or (C) could be true

   
   
   

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   NA

   Correct Option: B

   NA

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