191. Bakelite is a:

1. 1. acrylate

   
   
   

   2. silicon varnish

   
   
   

   3. thermoplastic synthetic resin

   
   
   

   4. phenol formaldehyde resin

   
   
   

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1. View Hint View Answer Discuss in Forum

   Bakelite is a phenol formaldehyde resin.

   Correct Option: D

   Bakelite is a phenol formaldehyde resin.

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192. Silicon steel is widely used in:

1. 1. cutting tools

   
   
   

   2. dies and punches

   
   
   

   3. electrical industry

   
   
   

   4. chemical industry

   
   
   

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1. View Hint View Answer Discuss in Forum

   Silicon steel is widely used in electrical industry.

   Correct Option: C

   Silicon steel is widely used in electrical industry.

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193. Silicon steel used for electrical purposes has silicon percentage of:

1. 1. 0.5%

   
   
   

   2. 25%

   
   
   

   3. 3.4%

   
   
   

   4. 12.5%

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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194. Gunmetal is an alloy of:

1. 1. 80% Cu + 15% Zn + 5% Sn

   
   
   

   2. 86% Cu + 9% Zn + 5% Sn

   
   
   

   3. 88% Cu + 2% Zn + 10% Sn

   
   
   

   4. 70% Cu + 10% Zn + 20% Sn

   
   
   

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1. View Hint View Answer Discuss in Forum

   Gunmetal is an alloy of 88% Cu + 2% Zn + 10% Sn.

   Correct Option: C

   Gunmetal is an alloy of 88% Cu + 2% Zn + 10% Sn.

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195. Aluminium has a higher atomic packing factor than molybdenum by about 6%. This means that:

1. 1. Aluminium is heavier than molybdenum

   
   
   

   2. The ratio of the volume of the unit cell to the volume of the atoms per unit cell is lower in aluminium

   
   
   

   3. The ratio of the number of atoms per unit cell to size of the cell is roughly equal to both

   
   
   

   4. The distance between atoms are equal for both

   
   
   

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1. View Hint View Answer Discuss in Forum

   The atomic packing factor (APF) is the ratio of volume of atoms per unit cell to the volume of the unit cell i.e.
   

   APF	Volume of atoms per unit cell
   	Volume of the unit cell

   
   Since aluminium has 6% greater atomic packing factor, then it has a lesser inverse ratio of volume of unit cell to volume of atoms per unit cell.

   Correct Option: B

   The atomic packing factor (APF) is the ratio of volume of atoms per unit cell to the volume of the unit cell i.e.
   

   APF	Volume of atoms per unit cell
   	Volume of the unit cell

   
   Since aluminium has 6% greater atomic packing factor, then it has a lesser inverse ratio of volume of unit cell to volume of atoms per unit cell.

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