61. The number of neutrons in dipositive zine ion (Zn²⁺, mass number 70 and atomic number 30) is

1. 1. 34

   
   
   

   2. 36

   
   
   

   3. 38

   
   
   

   4. 40

   
   
   

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   NA

   Correct Option: D

   NA

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62. Wavelength of X - rays is of the order of

1. 1. 1 mm

   
   
   

   2. 1 cm

   
   
   

   3. 1 micron

   
   
   

   4. 1 angstrom

   
   
   

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   NA

   Correct Option: D

   NA

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63. The number of unpaired electrons in Mn²⁺ is

1. 1. 1

   
   
   

   2. 3

   
   
   

   3. 4

   
   
   

   4. 5

   
   
   

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   NA

   Correct Option: D

   NA

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64. The atoms of the elements which have same number of neutrons are called

1. 1. Isobars

   
   
   

   2. Isotopes

   
   
   

   3. Isotones

   
   
   

   4. None

   
   
   

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   NA

   Correct Option: C

   NA

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65. CN^- ion is isoelectronic with

1. 1. N₂

   
   
   

   2. CO

   
   
   

   3. both a & b

   
   
   

   4. none

   
   
   

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   NA

   Correct Option: C

   NA

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