The number of electrons, neutrons and protons in a species are eq

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 Multiple Choice QuestionsMultiple Choice Questions

81.

The shortest wavelength of the line in hydrogen atomic spectrum of Lyman series when RH = 109678 cm-1 is

  • 1002.7 Å

  • 1215.67 Å

  • 1127.30 Å

  • 911.7 Å


82.

Which of the following are isoelectronic species?

(i) NH3

(ii) CH3+

(iii) NH2-

(iv) NH4+

Choose the correct answer from the codes given below.

  • (i), (ii), (iii)

  • (ii), (iii), (iv)

  • (i), (ii), (iv)

  • (i), (iii), (iv)


83.

The ratio of the frequency corresponding to the third line in Lyman series of hydrogen atomic spectrum to that of the first line in Balmer series of Li2+ spectrum is

  • 45

  • 54

  • 43

  • 34


84.

Which transition in the hydrogen atomic spectrum will have the same wavelength as the transition will have the same wavelength, n = 4 to n = 2 of He+ spectrum?

  • n = 4 to = 3

  • n = 2 to n = 1

  • n = 4 to n = 2

  • n = 3 to n = 1


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85.

The number of electrons, neutrons and protons in a species are equal to 10, 8 and 8 respectively. The proper symbol of the species

  • O816

  • O2-816

  • O-816

  • O818


B.

O2-816

From the given data, it is clear that the atomic number, Z or number of protons of the species is 8. Number of neutrons is also 8, hence atomic mass is 16. Since, the number of electrons are two more than the number of protons, hence it is a binegative, species. Thus, the species is O2-816.


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86.

A 600 W mercury lamp emits monochromatic radiation of wavelength 331.3 nm. How many photons are emitted from the lamp per second? (h = 6.626 x 10-34 Js; velocity of light = 3×108 ms-1).

  • 1 × 1019

  • 1 × 1022

  • 1 × 1021

  • 1 × 1023


87.

The shortest wavelength in hydrogen spectrum of Lyman series when RH = 109678 cm-1 is

  • 1002.7 Å

  • 1215.67 Å

  • 1127.30 Å

  • 911.7 Å


88.

The electrons, identified by quantum numbers n and l,

(I) = 3; l = 2; (II) = 5; l = 0; (III) = 4; l = 1; (IV) = 4; l = 2; (V) = 4; l = 0;

can be placed in order of increasing energy as-

  • I < V < III < IV < II

  • I < V < III < II < IV

  • V < I < III < II < IV

  • V < I < II < III < IV


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89.

The number of photons emitted per second by a 60 W source of monochromatic light of wavelength 663 nm is (h = 6 .63 × 10-34 Js)

  • 4 × 10-20

  • 1.5 × 1020

  • 3 × 10-20

  • 2 × 1020


90.

Energy released, when one atom of uranium undergoes nuclear fission according to the following reaction is (atomic mass of U = 235.060; n = 1.009; Ba= 143.881 and Kr = 89.94 7) about 

92U2350n1 → 56Ba14436Kr90 + 2 0n1

  • 235 MeV

  • 208 MeV

  • 931.5 MeV

  • 5.33 x 1023 MeV


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