In the hydrogen atom spectrum, the emission of the least energeti

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 Multiple Choice QuestionsMultiple Choice Questions

71.

90Th228 emits four alpha and one beta particles. Number of neutrons in daughter element is

  • 129

  • 190

  • 232

  • 138


72.

Which of the ions is colourless inspite of the presence of unpaired electrons ?

  • La3+

  • Eu3+

  • Gd3+

  • Lu3+


73.

Uncertainty in the position of an electron (mass= 9.1 x 10-31 kg) moving with a velocity 300 ms-1 accurate upon 0.001 % will be (h = 6.63 x 10-34 J-s)

  • 19.2 x 10-2 m

  • 5.76 x 10-2 m

  • 1.92 x 10-2 m

  • 3.84 x 10-2 m


74.

Uncertainty principle is valid for

  • Proton

  • Methane

  • Both (a) and (b)

  • 1 µm sized platinum particles


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75.

The energy of an electron is the 3S orbital ( excited state) of H- atom is

  • -1.5 eV

  • -13.6 eV

  • -3.4 eV

  • -4.53 eV


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76.

In the hydrogen atom spectrum, the emission of the least energetic photon takes place during the transition from n = 6 energy level to n = .......... energy level.

  • 1

  • 3

  • 5

  • 4


C.

5

According to the relation,

E  1λ  v  1nL2 - 1nU2

In hydrogen atom the emission of the least energetic photon take place only when change in energy is minimum. This is possible for an electron that is present in n = 6 and jumps to n = 5.


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77.

The threshold frequency of a metal corresponds to the wavelength of x nm. In two separate experiments A and B, incident radiations of wavelengths 1/2x nm and 1/4x nm respectively are used. The ratio of kinetic energy of the released electrons in experiment 'B' to that in experiment 'A' is

  • 1/3

  • 2

  • 4

  • 3


78.

The minimum values of uncertainties involved in the determination of both the position and velocity of a particle respectively are 1 × 10-10 m and 1 × 10-10 ms-1.Then, the mass (in kg) of the particle is

  • 5.270 × 10-15

  • 5.270 × 10-20

  • 5.270 × 10-16

  • 5.270 × 10-10


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79.

The number of electrons with azimuthal quantum number l = 1 and l = 2 for Cr in ground state respectively are

  • 12, 5

  • 12, 4

  • 16, 5

  • 16, 4


80.

In which one of the following, d-d transition involves absorption in the ultraviolet region?

  • [Cu(H2O)4]2+

  • [Ti(H2O)6]3+

  • [Co(NH3)6]3+

  • [Co(CN)6]3-


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