51. Which one of the following is most reactive ?

1. 1. White phosphorus

   
   
   

   2. Black phosphorus

   
   
   

   3. Violet phosphorus

   
   
   

   4. Scarlet phosphorus

   
   
   

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   NA

   Correct Option: A

   NA

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52. Which element is most abundant on earth's crust ?

1. 1. Ca

   
   
   

   2. C

   
   
   

   3. Si

   
   
   

   4. O

   
   
   

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   NA

   Correct Option: D

   NA

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53. Phosphorus is kept in

1. 1. Cold water

   
   
   

   2. Kerosene oil

   
   
   

   3. Alcohol

   
   
   

   4. Ammonia

   
   
   

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   NA

   Correct Option: A

   NA

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54. Which one of the following has highest ionization energy ?

1. 1. O

   
   
   

   2. S

   
   
   

   3. Se

   
   
   

   4. Te

   
   
   

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   NA

   Correct Option: A

   NA

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55. Nitrates of all metals are

1. 1. Unstable

   
   
   

   2. Coloured

   
   
   

   3. Insoluble in water

   
   
   

   4. Soluble in water

   
   
   

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   NA

   Correct Option: D

   NA

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