71. Cathode rays are

1. 1. electromagnetic wave

   
   
   

   2. stream of α - particle

   
   
   

   3. stream of electrons

   
   
   

   4. radiations

   
   
   

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   NA

   Correct Option: C

   NA

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72. Neutrino has

1. 1. charge +1, amss 1

   
   
   

   2. charge 0, mass 0

   
   
   

   3. charge -1, mass 1

   
   
   

   4. charge 0, mass 1

   
   
   

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   NA

   Correct Option: B

   NA

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73. Na⁺ ion is iso electronic with

1. 1. Li⁺

   
   
   

   2. Mg²⁺

   
   
   

   3. Ca²⁺

   
   
   

   4. Ba²⁺

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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74. Which electromagnetic radiation is emitted by radioactive substances

1. 1. y - rays

   
   
   

   2. Radio waves

   
   
   

   3. micro waves

   
   
   

   4. x - ray

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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75. Which of the following has the longest wave length ?

1. 1. ultraviolet radiation

   
   
   

   2. y - radiation

   
   
   

   3. visible radiation

   
   
   

   4. infra red radiation

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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