126. With respect to a completely filled band, which one of the following statements is correct?

1. 1. The total wave vector and the total velocity of all electrons in the band is always zero

   
   
   

   2. The total wave vector and the total velocity of all electrons in the band is not necessarily zero

   
   
   

   3. Both (A) and (B) above

   
   
   

   4. None of the above

   
   
   

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   NA

   Correct Option: B

   NA

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127. 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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128. A solder is an alloy of:

1. 1. Tin and lead

   
   
   

   2. Lead and zinc

   
   
   

   3. Zinc and copper

   
   
   

   4. Copper and aluminium

   
   
   

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   A solder is an alloy of tin and lead.

   Correct Option: A

   A solder is an alloy of tin and lead.

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129. Amorphous materials:

1. 1. Glass

   
   
   

   2. Silver

   
   
   

   3. Lead

   
   
   

   4. Zinc

   
   
   

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   NA

   Correct Option: A

   NA

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130. Electrical resistances are made from:

1. 1. Elinvar

   
   
   

   2. Duralumin

   
   
   

   3. Constantan

   
   
   

   4. Monel metal

   
   
   

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   Electrical risistances are made from constantan.

   Correct Option: C

   Electrical risistances are made from constantan.

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