1. The echo will be heard if the original sound reflected by an obstacle in

1. 1. 10 s

   
   
   

   2. 0.50 s

   
   
   

   3. 15 s

   
   
   

   4. 0.1 s

   
   
   

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   NA

   Correct Option: D

   NA

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2. Learned Indian classical vocalists do not like the accompaniment of a harmonium because

1. 1. Tempered scale is used in the harmonium

   
   
   

   2. Diatonic scale is used in the harmonium

   
   
   

   3. Notes of the harmonium are too shrill

   
   
   

   4. Intensity of the notes of the harmonium is too large

   
   
   

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   NA

   Correct Option: A

   NA

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3. Consider the following statements :
   1. X - rays show transverse wave characteristics
   2. X - rays can eject electrons from certain metal surfaces
   3. X - rays of 0.1 A^° are harder than X - rays of 0.2 A^°
   Which of the statements given above is / are correct ?
   
   

1. 1. 1 only

   
   
   

   2. 1 and 2 only

   
   
   

   3. 2 an 3 only

   
   
   

   4. 1, 2 and 3

   
   
   

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   NA

   Correct Option: D

   NA

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4. A radar beam consists of

1. 1. X - rays

   
   
   

   2. Infrared rays

   
   
   

   3. Ultraviolet - rays

   
   
   

   4. Microwaves

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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5. The velocities of sound in air and water are 336 m / s and 1470 m/s respectively. Two sources producing waves of wavelength 6 m and 7 m sounded togather will produce beats

1. 1. That can be heard in both the media

   
   
   

   2. That can be heard only in water and not in air

   
   
   

   3. That can be heard only in air and not in water

   
   
   

   4. That can not be heard in either media

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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