98Cf246  was formed along with a neutron when an unknown rad

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 Multiple Choice QuestionsMultiple Choice Questions

31.

β-emission is always accompanied by

  • formation of antineutrino and α-particle

  • emission of α-particle and γ-ray

  • formation of antineutrino and γ-ray

  • formation of antineutrino and positron


32.

An atomic nucleus having low n/p ratio tries to find stability by

  • the emission of an α-particle

  • the emission of a positron

  • capturing an orbital electron (K-electron capture)

  • emission of a β-particle


33.

( G7632, Se7634) and ( Si3014, S3216) are example of 

  • isotopes and isobars

  • isobars and isotones

  • isotones and isotopes

  • isobars and isotopes


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34.

98Cf246  was formed along with a neutron when an unknown radioactive substance was bombarded with 6C12. The unknown substance was 

  • 91Pa234

  • 90Th234

  • 92U235

  • 92U238


C.

92U235

Let, the unknown radioative substance be AYX.AYX + C126  Cf24698 + n10On comparing atomic numbers, we get X + 6 = 98 + 0 X= 98-6 =92 On comparing mass numbers, we get Y+ 12 = 246 + 1 Y= 247-12 = 235 Since, uranium has the atomic number 92, thus,the given unknown substance was U23592.


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35.

Identify the correct statement.

  • Quantum numbers (n, l, m, s) are arbitrarily

  • All the quantum numbers (n, l, m, s) for any pair of electron in an atom can be identical under special circumstance

  • All the quantum numbers (n, l, m, s) may not be required to describe an electron of an atom completely

  • All the quantum numbers (n, l, m, s) are required to describe an electron of an atom completely


36.

Na2411 is radioactive and it decays to 

  • F209 and α- practicle

  • Al2413 and positron

  • Na2311 and neutron

  • Mg2412 and β- parcticles


37.

Which one of the following characteristics belongs to an electrophile?

  • It is any species having electron deficiency which reacts at an electron rich C-centre

  • It is any species having electron enrichment, that reacts at an electron deficient C-centre

  • It is cationic in nature

  • It is anionic in nature


38.

Which of the following does not represent the mathematical expression for the Heisenberg uncertainty principle?

  • x·P h/ (4π)

  • x·νh/(4πm)

  • E·th/(4π)

  • E·xh(4π)


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39.

The energy of an electron in first Bohr orbit of H-atom is -13.6 eV. The possible energy value of electron in the excited state of Li2+ is

  • -122.4 eV

  • 30.6 eV

  • -30.6 eV

  • 13.6 eV


40.

The representation of the ground state electronic configuration of He by box-diagram as  is wrong because it violates

  • Heisenberg's uncertainty principle

  • Bohr's quantization theory of angular momenta

  • Pauli exclusion principle

  • Hund's rule


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