116. Out of the following, the one which can pass through 20 cm thickness of steel is

1. 1. α - rays

   
   
   

   2. β - rays

   
   
   

   3. y - rays

   
   
   

   4. ultraviolet rays

   
   
   

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   NA

   Correct Option: C

   NA

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117. Which one of the following is not a radioactive element ?

1. 1. Uranium

   
   
   

   2. Thorium

   
   
   

   3. Radium

   
   
   

   4. Casmium

   
   
   

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   NA

   Correct Option: D

   NA

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118. An atomic pile is used for

1. 1. Producing X - rays

   
   
   

   2. Conducting nuclear fission

   
   
   

   3. Conducting thermonuclear fission

   
   
   

   4. Temperature

   
   
   

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   NA

   Correct Option: B

   NA

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119. The nucleus of an atom consists of

1. 1. Electrons and protons

   
   
   

   2. Neutrons only

   
   
   

   3. Neutrons and protons

   
   
   

   4. Protons, electrons and neutrons

   
   
   

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   NA

   Correct Option: C

   NA

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120. The mass number of a nucleus is

1. 1. Always less than its atomic number

   
   
   

   2. Always more than its atomic number

   
   
   

   3. Some times more than and some times equal to its atomic number

   
   
   

   4. None of the above

   
   
   

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   NA

   Correct Option: C

   NA

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