How many neutrons are there in nucleus 'X', if it gives

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391.

The isoelectronic pair is

  • Cl2O, ICl2-

  • ICl2-, ClO2

  • IF2+, I3-

  • ClO2-, ClF2+


392.

α-Particles can be detected using

  • thin aluminium sheet

  • barium sulphate

  • zinc sulphide screen

  • gold foil


393.

The most probable radius (in pm) for finding the electron in He+ is

  • 0.0

  • 52.9

  • 26.5

  • 105.8


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394.

How many neutrons are there in nucleus 'X', if it gives 7N14 after two successive β - particle emissions ?

  • 7

  • 10

  • 14

  • 09


D.

09

The atomic number of radioactive element increases by one by the emission of 1 β - particle. Hence, after the emission of 2 β -particles, there will be an increase of 2 units in atomic number.

Hence, 5X14 -2β -particle 7N14

Hence, the number of neutrons in parent element (X) = 14 - 5 = 9


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395.

The energy equivalent to 1 amu., is :

  • 931.1 MeV

  • 1.492 x 1013 erg

  • 1000 J

  • 107 erg


396.

Which particle can be used to change 13Al27 into 15P30 ?

  • Neutron

  • α - particle

  • Proton

  • Deuteron


397.

According to Bohr, the angular momentum of an electron, in any orbit, should be :

  • h/2π

  • nh/2π

  • h/mv

  • 2π/nh


398.

Quantum numbers of an atom can be defined on the basis of :

  • Hund's rule

  • Pauli's exclusion principle

  • Aufbau's principle

  • Heisenberg's uncertainty principle


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399.

Which of the following has maximum energy ?


  • 3s                      3p                                     3d
                 

  • 3s                      3p                                   3d
               

  • 3s                     3p                                     3d
             

  • 3s                    3p                                 3d
               


400.

Spectrum of Li2+ is similar to that of :

  • H

  • Be

  • He

  • Ne


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