151. An explosion takes place on the surface of moon. An astronaut at some distance from the site of explosion will

1. 1. Observe light and hear sound caused by the explosion

   
   
   

   2. Observe light but not hear sound caused by the explosion

   
   
   

   3. Hear sound but not observe light caused by the explosion

   
   
   

   4. Neither hear sound nor observe light caused by the explosion

   
   
   

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   N/A

   Correct Option: B

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152. What is viewed through an electron microscope?

1. 1. Electrons and other elementary particles

   
   
   

   2. Structure of bacteria and viruses

   
   
   

   3. Inside of human stomach

   
   
   

   4. Inside of the human eye

   
   
   

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   N/A

   Correct Option: B

   N/A

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153. To observe diffraction, the size of the obstacles

1. 1. Should be of the same order as the wavelength

   
   
   

   2. Should be much larger than the wavelength

   
   
   

   3. Has no relation to wavelength

   
   
   

   4. Should be exactly half the wavelength

   
   
   

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   N/A

   Correct Option: A

   N/A

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154. Plane mirrors A and B are kept at angle 0 with respect to each other. Light falls on A is reflected then falls on B and is reflected. The emergent ray is oppsite to the incident direction. The angle 0 is equal to

1. 1. 30°

   
   
   

   2. 45°

   
   
   

   3. 60°

   
   
   

   4. 90°

   
   
   

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   N/A

   Correct Option: D

   N/A

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155. Why is red light employed for danger signals ?

1. 1. Red colour is soothing to the eye

   
   
   

   2. Human eye is most sensitive to red colour

   
   
   

   3. Red light is scattered least

   
   
   

   4. Red light is scattered most

   
   
   

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1. View Hint View Answer Discuss in Forum

   N/A

   Correct Option: C

   N/A

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