An electron is moving in Bohr's fourth orbit. Its de-Broglie wave

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 Multiple Choice QuestionsMultiple Choice Questions

111.

The atomic numbers of elements X,Y and Z are 19, 21 and 25 respectively. The number of electrons present in the M-shell of these elements follow the order

  • Z > X > Y

  • X > Y > Z

  • Z > Y > X

  • Y > Z > X


112.

Which of the following elements has least number of electrons in its M shell ?

  • K

  • Mn

  • Ni

  • Sc


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113.

An electron is moving in Bohr's fourth orbit. Its de-Broglie wave length is λ. What is the circumference of the fourth orbit ?

  • 2/λ

  • 4/λ


C.

According to Bohr's concept, an electron always move in the orbit with angular momentum (mvr) equal to nh /2Π.

 mvr = nh2πor  r=n2π·hmv  or r=2π(From de - Broglie equation, λ = hmv)for fourth orbit n= 4           r= 2λπ circumference = 2πr = 2π  × 2λπ= 4λ


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114.

Which of the following is correct?

  • 1H1 and 2He3 are isotopes

  • 6C14 and 7N14 are isotopes

  • 19K39 and 20Ca40 are isotones

  • 9F19 and 11Na24 are isodiaphers


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115.

What is the correct order of spin only magnetic moment (in BM) of Mn2+, Cr2+ and V2+ ?

  • Mn2+ > V2+ > Cr2+

  • V2+ > Cr2+ > Mn2+

  • Mn2+ > Cr2+ > V2+

  • Cr2+ > V2+ > Mn2+ 


116.

The uncertainties in the velocities of two particles A and B are 0.05 and 0.02 m/s-1 respectively. The mass of B is five times to that of mass A. What is the ratio of uncertainities xAxB in their positions?

  • 2

  • 0.25

  • 4

  • 1


117.

The energy of a photon is 3 × 10-12 ergs. What is its wavelength in nm ?

(h = 6.62 × 10-27 ergs ; c = 3 × 1010 cm/s)

  • 662

  • 1324

  • 66.2

  • 6.62


118.

Which of the following is not correct ?

  • Nuclei of atoms participate in nuclear reactions

  • 20Ca40 and 18Ar40 are isotones

  • 1 amu of mass defect is approximately equal to 931.5 MeV.

  • Uranium (U238) series is known as (4n + 2) series.


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119.

An electronic transition in hydrogen atom results in the formation of Hα line of hydrogen in Lyman series, the energies associated with the electron in each of the orbits involved in the transition (in kcal mol-1) are 

  • -313,6, - 34.84

  • -313.6, - 78.4

  • -78.4,- 34.84

  • -78.4,-19.6


120.

The velocities of two particles A and B are 0.05 and 0.02 ms-1 respectively. The mass of B is five times the mass of A. The ratio of their de-Broglie's wavelength is

  • 2 : 1

  • 1 : 4

  • 1 : 1

  • 4 : 1


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