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Atoms · Question 14

NEET (UG) 2020MCQEasy📈 Topic in 75% papers+4−1
1

For which one of the following, Bohr model is not valid?

  1. Singly ionised helium atom (He+)
  2. Deuteron atom
  3. Singly ionised neon atom (Ne+)
  4. Hydrogen atom

Answer

(3) Singly ionised neon atom (Ne+)

Solution

As per NCERT, Bohr model is applicable only to hydrogen and hydrogen-like (single-electron) species.

He+: Z = 2, one electron ⇒ hydrogen-like, Bohr model valid.

Deuteron atom (deuterium): one electron ⇒ Bohr model valid.

Hydrogen atom: one electron ⇒ Bohr model valid.

Ne+: Z = 10, number of electrons = 10 - 1 = 9

∴ It is a many-electron species; electron–electron interactions are not included in Bohr model, so the model is not valid for Ne+.

Answer: (3)

NEET (UG) 2020

Keep practising — Atoms

2

-particle consists of :

  1. 2 electrons, 2 protons and 2 neutrons
  2. 2 electrons and 4 protons only
  3. 2 protons only
  4. 2 protons and 2 neutrons only
NEET (UG) 2019
3

The total energy of an electron in an atom in an orbit is -3.4 eV. Its kinetic and potential energies are, respectively.

  1. 3.4 eV, -6.8 eV
  2. 3.4 eV, 3.4 eV
  3. -3.4 eV, -3.4 eV
  4. -3.4 eV, -6.8 eV
NEET (UG) 2019
4

The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom, is

  1. 1 : 1
  2. 1 : -1
  3. 2 : -1
  4. 1 : -2
NEET 2018
5

The ratio of wavelengths of the last line of Balmer series and the last line of Lyman series is

  1. 1
  2. 4
  3. 0.5
  4. 2
NEET 2017
6

Given the value of Rydberg constant is 107 m-1, the wave number of the last line of the Balmer series in hydrogen spectrum will be

  1. 0.25 107 m-1
  2. 2.5 107 m-1
  3. 0.025 104 m-1
  4. 0.5 107 m-1
NEET 2016 (Phase 1)
7

When an -particle of mass m moving with velocity v bombards on a heavy nucleus of charge Ze, its distance of closest approach from the nucleus depends on m as

  1. 1m2
  2. m
  3. 1m
  4. 1 m
NEET 2016 (Phase 1)
8

Electrons of mass m with de-Broglie wavelength fall on the target in an X-ray tube. The cutoff wavelength ( 0) of the emitted X-ray is

  1. 0 = 2mc 2h
  2. 0 = 2hmc
  3. 0 = 2m2c2 3h2
  4. 0 =
NEET 2016 (Phase 2)
9

If an electron in a hydrogen atom jumps from the 3rd orbit to the 2nd orbit, it emits a photon of wavelength . When it jumps from the 4th orbit to the 3rd orbit, the corresponding wavelength of the photon will be

  1. 1625
  2. 916
  3. 207
  4. 2013
NEET 2016 (Phase 2)
10

In the spectrum of hydrogen, the ratio of the longest wavelength in the Lyman series to the longest wavelength in the Balmer series is

  1. 275
  2. 527
  3. 49
  4. 94
AIPMT 2015
11

Consider 3rd orbit of He+ (Helium), using non-relativistic approach, the speed of electron in this orbit will be [given K = 9 109 constant, Z = 2 and h (Planck's Constant) = 6.6 10-34 J s]

  1. 0.73 106 m/s
  2. 3.0 108 m/s
  3. 2.92 106 m/s
  4. 1.46 106 m/s
AIPMT 2015 (Cancelled)

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