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111.

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


B.

-313.6, - 78.4

Energy of an electron in nth orbit,

En-2π2k2mZ2e4n2h2

On substituting the value of k, m, e and h, we get,

 En = -2.172 × 10-18Z2n2 J atom-1     = -1311.8 Z2n2 kJ mol-1     = -313.52 Z2n2 kcal mol-1    [ 1 kcal = 4.184 kJ]

For H-atom, Z = 1

For Lyman series, n1 = 1; n2 = 2

Energy of electron in n1 orbit 

     = -313.52 × (1)2(1)2 kcal mol-1

     = -313.52 kcal mol-1 ≈ -313.6 kcal mol-1

Energy of electron in n2 orbit 

    =- 313.52 × (1)2(2)2 kcal mol-1= -313.524 kcal mol-1

    = -78.38 kcal mol-1


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112.

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


113.

The wavelengths of electron waves in two orbits is 3 : 5. The ratio of kinetic energy of electrons will be 

  • 25 : 9

  • 5 : 3

  • 9 : 25

  • 3 : 5


114.

Which one of the following conditions is incorrect for a well behaved wave function (Ψ)?

  • Ψ must be fine

  • Ψ must be single valued

  • Ψ must be infinite

  • Ψ must be continuous


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115.

Which one of the following frequencies of radiation (in Hz) has a wavelength of 600 nm?

  • 2.0 × 1013 

  • 5.0 × 1016 

  • 2.0 × 1014 

  • 5.0 × 1014 


116.

According to Bohr's theory which one of the following values of angular momentum of hydrogen atom is not permitted?

  • 1.25 hπ

  • hπ

  • 1.5  hπ

  • 0.5 hπ


117.

The number of radial nodes of 3s and 2p orbitals respectively are

  • 0, 2

  • 2, 0

  • 1, 2

  • 2, 1


118.

The quantum number which explains the line spectra observed as doublets in case of hydrogen and alkali metals and doublets and triplets in case of alkaline earth metals is

  • spin

  • azimuthal

  • magnetic

  • principal


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119.

A compound absorbs light in the wavelength region 490-500 nm. Its complementary colour is

  • red

  • blue

  • orange

  • blue-green


120.

Which of the following sets of quantum numbers is correct for an electron in 3d-orbital?

  • n = 3; l = 2; m = -3; s = +12

  • n = 3; l = 3; m = +3; s = -12

  • n = 3; l = 2; m = -2; s = +12

  • n = 3; l = 2; m = -3; s = -12


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