Atoms

15 Questions | By Jagranjosh | Last updated: Apr 3, 2014 | Total Attempts: 499

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Atoms

Time : 30 Minute

Questions and Answers

1.

The energy equivalent to one atomic mass unit is:
- A.
- B.
- C.
  
  9.23 Mev
- D.
  
  931 MeV
2.

The ratio of radii of orbits corresponding to first and second excited states of hydrogen atom is:
- A.
  
  1 : 3
- B.
  
  1 : 2
- C.
  
  2: 3
- D.
  
  4 : 9
3.

The series of hydrogen spectrum which lies in visible region is:
- A.
  
  Lymann series
- B.
  
  Balmer series
- C.
  
  Paschen series
- D.
  
  None of the above
4.

The order of velocity of electron in ground sate of hydrogen is:
- A.
  
  10 m/s
- B.
  
  10⁶ m/s
- C.
  
  10^-6 m/s
- D.
  
  10⁸ m/s
5.

The diameter of the first orbit of the hydrogen atom is of the order of:
- A.
  
  0.5 Ǻ
- B.
  
  1 Ǻ
- C.
  
  2 Ǻ
- D.
  
  4 Ǻ
6.

The simple Bohr model cannot be directly applied to calculate the energy levels of an atom with many electrons. This is because:
- A.
  
  Of the electrons not being subject to a central force
- B.
  
  Of the electrons colliding with each other
- C.
  
  Of screening effect
- D.
  
  The force between the nucleus and an electron will no longer be given by Coulomb’s Law
7.

Two H atoms in the ground state collide inelastically. The maximum amount by which their combined kinetic energy is reduced is:
- A.
  
  10.20 eV
- B.
  
  20.40 eV
- C.
  
  13.6 eV
- D.
  
  27.2 eV
8.

Hydrogen atom is excited from ground sate to another state with principal quantum number equal to 4. Then the number of spectral lines in the emission spectra will be:
- A.
  
  2
- B.
  
  3
- C.
  
  5
- D.
  
  6
9.

Taking the Bohr radius as a_o = 53pm, the radius of Li²⁺ ion in its ground state, on the basis of Bohr’s model, will be about:
- A.
  
  53 pm
- B.
  
  27 pm
- C.
  
  18 pm
- D.
  
  13 pm
10.

Which of the following transitions in a hydrogen atom emit a photon of highest frequency?
- A.
  
  N = 2 to n = 6
- B.
  
  N = 6 to n = 2
- C.
  
  N = 1 to n = 2
- D.
  
  N = 2 to n = 1
11.

In a Rutherford scattering experiment, when a projectile of charge Q and mass M approaches a target nucleus of charge q and mass m, the distance of closest approach is r. The energy of the projectile is:
- A.
  
  Directly proportional to mass M
- B.
  
  Directly proportional to
- C.
  
  Directly proportional to Qq
- D.
  
  Directly proportional to Q
12.

The positron was discovered by:
- A.
  
  Chadwick
- B.
  
  Bohr
- C.
  
  Maxwell
- D.
  
  Anderson
13.

Energy of electron in t6hye 1^st orbit of H-atom is:
- A.
  
  –13.6 MeV
- B.
  
  –13.6 eV
- C.
  
  –13.6 J
- D.
  
  13.6 J
14.

With increasing quantum number, the energy difference between adjacent energy levels in atoms:
- A.
  
  Increases
- B.
  
  Decreases
- C.
  
  Remains constant
- D.
  
  First increases then decreases
15.

. Let there be a system of energy levels of a certain atom. When the system moves from 2E level to E, a photon of wavelength λ is emitted. The wavelength of photon produced during its transition from level to E is:
- A.
- B.
- C.
- D.