(32Ge76, 34Se76) and (14Si30, 16S32) are examples of f

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 Multiple Choice QuestionsMultiple Choice Questions

421.

What is the maximum numbers of electrons that can be associated with the following set of quantum numbers? n = 3, l = 1 and m =-1.

  • 10

  • 6

  • 4

  • 2


422.

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 β -particle


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423.

(32Ge7634Se76) and (14Si3016S32) are examples of

  • isotopes and isobars

  • isobars and isotones

  • isotones and isotopes

  • isobars and isotopes


B.

isobars and isotones

32Ge76 and 34Se76 have the same mass number but different atomic number, therefore, they are isobars.

Number of neutrons, in

 14Si30 = 30 - 14 = 16

16Si32 = 32 - 16 = 16

Because of the presence of same number pf neutrons, 14Si30 and 16S32, they are known as isotones.


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424.

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

  • 91Pa234

  • 90Th234

  • 92U235

  • 92U238


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425.

Based on equation E = -2.178 × 10-18 J Z2n2 certain conclusions are written. Which of them is not correct?

  • The negative sign in equation simply means that the energy of electron bound to the nucleus is lower than it would be if the electrons were at the infinite distance from the nucleus.

  • Larger the value of n, the larger is the orbit radius

  • Equation can be used to calculate the change in energy when the electron changes orbit.

  • For n = 1 the electron has a more negative energy than it does for n = 6 which means that the electron is more loosely bound in the smallest allowed orbit.


426.

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


427.

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


428.

The electronic transitions from n = 2 to n = 1 will produce shortest wavelength in (where n = principal quantum state)

  • Li2+

  • He+

  • H

  • H+


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429.

A radioactive atom MYX emits two α particles and one β particle successively. The number of neutrons in the nucleus of the product will be:

  • X - 4 - Y

  • X - Y - 5

  • X - Y - 3

  • X - Y - 6


430.

1 mole of photon, each of frequency 2500 s-1, would have approximately a total energy of

  • 10 erg

  • 1 J

  • 1 eV

  • 1 MeV


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