The correct set of four quantum numbers for the valence electron

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 Multiple Choice QuestionsMultiple Choice Questions

1.

A stream of electrons from a heated filament was passed between two charged plates kept at a potential difference V esu. If e and m are charge and mass of an electron, respectively, then the value of h/λ (where λ is wavelength associated with electron wave) is given by:

  • 2meV

  • square root of mev
  • square root of 2 meV end root
  • square root of 2 meV end root
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2.

Which of the following is the energy of a possible excited state of hydrogen?

  • +13.6 eV

  • -6.8 eV

  • -3.4 eV

  • -3.4 eV

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3.

The correct set of four quantum numbers for the valence electrons fo rubidium atom (Z = 37) is

  • 5,0,0, +1/2

  • 5,1,0,6+1/2

  • 5,1,1,+1/2

  • 5,1,1,+1/2


A.

5,0,0, +1/2

the atomic number of Rb (Z) = 37
Thus, its electronic configuration [Kr]5s1. since the last electron or valence electron enters in 5s subshell. So, the quantum numbers are n = 5, l =0(for s orbital) m=0 
(m = +l to -l), s = +1/2 or -1/2

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4.

Energy of an electron is given by
E =- 2.178 x 10-18open parentheses straight Z squared over straight n squared close parentheses
Wavelength of light required to excite an electron in a hydrogen atom from level n =1 to n=2 will be (h=6.62 x 1034 Js and c = 3.0 x 108 ms-1

  • 1.214 x 10-7 m

  • 2.816 x 10-7 m

  • 6.500 x 10-7 m

  • 6.500 x 10-7 m

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5.

The electrons identified by quantum numbers n and l:
(a) n = 4, l = 1 (b) n = 4, l = 0 (c) n = 3, l = 2 (d) n = 3 , l = 1
Can be placed in order of increasing energy as

  • (c) < (d) < (b) < (a) 

  • (d) < (b) < (c) < (a)

  • (b) < (d) < (a) < (c)

  • (b) < (d) < (a) < (c)

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6.

A gas absorbs a photon of 355 nm and emits at two wavelengths. If one of the emission is at 680 nm, the other is at

  • 1035 nm

  • 325 nm

  • 743 nm 

  • 743 nm 

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7.

The ionization energy of He+ is 19.6 x 10–18 J atom–1. The energy of the first stationary state (n = 1) of Li2+ is

  • 4.41 x 10-16 J atom–1

  • -4.41 x 10-17 J atom–1

  • -2.2 x 10-15 J atom–1.

  • -2.2 x 10-15 J atom–1.

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8.

The radius of the second Bohr orbit for the hydrogen atom is :
(Plank's const. h = 6.6262 × 10–34 Js ; mass of electron = 9.1091 × 10–31 kg ; charge of electron
e = 1.60210 × 10–19 C ; permittivity of vacuum
∈0 = 8.854185 × 10–12 kg–1 m–3 A2)

  • 1.65Å

  • 4.76Å

  • 0.529Å

  • 0.529Å

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9.

Calculate the wavelength (in nanometer) associated with a proton moving at 1.0 × 10ms–1
(Mass of proton = 1.67 × 10–27 kg and h = 6.63 ×10–34Js)

  • 0.032 nm

  • 0.40 nm

  • 2.5 nm

  • 2.5 nm

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10.

In an atom, an electron is moving with a speed of 600m/s with an accuracy of 0.005%. Certainty with which the position of the electron can be located is ( h = 6.6 x10-34 kgm2s-1 mass of electron, em= 9.1 x10-31kg)

  • 1.52 x 10-4m

  • 5.10 x 10-3m

  • 1.92 x 10-3m

  • 1.92 x 10-3m

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