136. The strongest force in the nature is

1. 1. Electric force

   
   
   

   2. Gravitational force

   
   
   

   3. Nuclear force

   
   
   

   4. Magnetic force

   
   
   

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   NA

   Correct Option: C

   NA

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137. Which of the following has the longest de Broglie wavelength if they are moving with same velocity ?

1. 1. Neutron

   
   
   

   2. Proton

   
   
   

   3. α - particle

   
   
   

   4. β - particle

   
   
   

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   NA

   Correct Option: D

   NA

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138. Cathode rays enter an electric field normal to the lines of force. Then their path in the electric field is

1. 1. Straight line

   
   
   

   2. Ellipse

   
   
   

   3. Circle

   
   
   

   4. Parabola

   
   
   

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   NA

   Correct Option: D

   NA

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139. In a nuclear reactor, cadmium rods are used to

1. 1. Speed up neutrons

   
   
   

   2. Slow down neutrons

   
   
   

   3. Absorb neutrons

   
   
   

   4. Produce neutrons

   
   
   

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   NA

   Correct Option: C

   NA

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140. The ratio of specific charges of an α - particle to that of a proton is

1. 1. 1 / 3

   
   
   

   2. 1 / 2

   
   
   

   3. 1 / 1

   
   
   

   4. 2 / 1

   
   
   

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   NA

   Correct Option: B

   NA

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