221. Investment casting uses... A as pattern material and is preferred for small parts with .... B ____designs. A. wax/resin coated sand B. simple/intricate

1. 1. A. wax B. intricate

   
   
   

   2. B. wax A. intricate

   
   
   

   3. A. wax B.

   
   
   

   4. B. wax A.

   
   
   

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   A. wax B. intricate

   Correct Option: A

   A. wax B. intricate

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222. The number of atoms per unit cell and the number of slip systems, respectively, for a facecentered cubic (FCC) crystal are

1. 1. 3, 3

   
   
   

   2. 3, 12

   
   
   

   3. 4, 12

   
   
   

   4. 4 ,48

   
   
   

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   No of atoms per unit cell in FCC ⇒
   
   

   =	1	× 8 (each corner) +	1	× 6 (each face) = 1 + 3 = 4
   	8		2

   
   No. of slip systems in FCC are 12.

   Correct Option: C

   No of atoms per unit cell in FCC ⇒
   
   

   =	1	× 8 (each corner) +	1	× 6 (each face) = 1 + 3 = 4
   	8		2

   
   No. of slip systems in FCC are 12.

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223. The crystal structure of aluminium is

1. 1. body-centred cubic

   
   
   

   2. face-centred cubic

   
   
   

   3. close-packed hexagonal

   
   
   

   4. body-centred tetragonal

   
   
   

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   NA

   Correct Option: B

   NA

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224. The atomic packing factor for a material with body centered cubic structure is _______ .

1. 1. APF = 0.68

   
   
   

   2. APF = 1.68

   
   
   

   3. APF = 0.78

   
   
   

   4. APF = - 1.68

   
   
   

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   4r = a√3
   
   

   a =	4r
   	√3

   
   APF = 0.68

   Correct Option: A

   4r = a√3
   
   

   a =	4r
   	√3

   
   APF = 0.68

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225. The crystal structure of austenite is

1. 1. body centered cubic

   
   
   

   2. face centered cubic

   
   
   

   3. hexagonal closed packed

   
   
   

   4. body centered tetragonal

   
   
   

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   γ - Austenite has FCC Structure.

   Correct Option: C

   γ - Austenite has FCC Structure.

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