The emission spectrum of hydrogen discovered first and the region

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 Multiple Choice QuestionsMultiple Choice Questions

21.

C6H5F18 is a F18  radio-isotope labelled organic compound. F18 decays by positron emission. The product resulting on decay is 

  • C6H5O18

  • C6H5Ar19

  • B12C5H5F

  • C6H5O16


22.

The energy required to break one mole of hydrogen-hydrogen bonds in H2 is 436 kJ. What is the longest wavelength of light required to break a single hydrogen-hydrogen bond?

  • 68.5nm

  • 137nm

  • 274nm

  • 584nm


23.

An element E loses one α and two β particles in three successive stages. The resulting elemenl wiil be

  • an isobar of E

  • an isotone of E

  • an isotope of E

  • E itself


24.

Which one of the following corresponds to a photon of highest energy?

  • λ = 300 mm

  • v = 3 × 108 s-1

  • v = 30 cm-1

  • ε = 6.626 × 10-27 J


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25.

The time taken for an electron to complete one revolution in Bohr orbit of hydrogen atom is

  • 4m2πr2n2h2

  • n2h24mr2

  • 4π2mr2nh

  • nh4π2mr2


26.

Amongst the following, which should have the highest rms speed at the same temperature?

  • SO2

  • CO2

  • O2

  • H2


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27.

The emission spectrum of hydrogen discovered first and the region of the electromagnetic spectrum in which it belongs, respectively are

  • Lyman, ultraviolet

  • Lyman, visible

  • Balmer, ultraviolet

  • Balmer, visible


D.

Balmer, visible

In 1885, Balmer for the first time showed that the wave numbers of spectral lines present in the visible region in hydrogen spectrum are given by

             ν-(cm-1)= 1096771(2)2-1n2

Here, n =3,4,5, ...
Thus, Balmer spectrum of hydrogen was discovered first and it lies in the visible region.


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28.

The electronic configuration of Cu is

  • [Ne] 3s2,3p6,3d9,4s2

  • [Ne] 3s2,3p6, 3d10, 4s1

  • [Ne] 3s2,3p6, 3d3,4s2, 4p6

  • [Ne] 3s2,3p6,3d5,4s2,4p4


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29.

As per de-Broglie's formula a macroscopic particle of mass 100 g and moving at a velocity of 100 cm s-1 will have a wavelength of

  • 6.6 x 10-29 cm

  • 6.6 x 10-30 cm

  • 6.6 x 10-31 cm

  • 6.6 x 10-32 cm


30.

During the emission of a positron from a nucleus, the mass number of the daughter element remains the same but the atomic numbe

  • is decreased by 1 unit

  • is decreased by 2 units

  • is increased by 1 unit

  • remains unchanged


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