81. Some common mediums in which speed of sound of sound?
    1. Air
    2. Steel
    3. Copper
    4. Water
    What is the correct increasing order of the speed of sound ?

1. 1. 1 < 4 < 2 < 3

   
   
   

   2. 4 < 1 < 2 < 3

   
   
   

   3. 1 < 4 < 3 < 2

   
   
   

   4. 4 < 1 < 3 < 2

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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82. Which one of the following is the correct sequence of wavelengths of radiations ?

1. 1. UV > Green > IR > Hard X - rays

   
   
   

   2. IR > Green > UV > Hard X - rays

   
   
   

   3. UV > Hard > IR > Green

   
   
   

   4. IR > Hard X - rays > Green > UV

   
   
   

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   NA

   Correct Option: B

   NA

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83. An accelerated electron would produce

1. 1. ∝ - rays

   
   
   

   2. y - rays

   
   
   

   3. β - rays

   
   
   

   4. E.M. rays

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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84. The audible frequency range of a human ear is

1. 1. 20 hertz to 200 hertz

   
   
   

   2. 2 hertz to 20 hertz

   
   
   

   3. 200 hertz to 2000 hertz

   
   
   

   4. 20 hertz to 20000 hertz

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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85. The temperature at which the speed of sound in air becomes double its value of 0^°C is

1. 1. 1092^°C

   
   
   

   2. 189 K

   
   
   

   3. 819^°C

   
   
   

   4. 546^°C

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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