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Atoms

JEE Main 2025 (Online) 3rd April Evening ShiftMCQEasy📈 Topic in 29% papers+4−1
Ques. 1JEE Main 2025, 3 April (Evening Shift)

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. In the light of the above statements, choose the correct answer from the options given below

  1. A is true but R is false
  2. Both A and R are true and R is the correct explanation of A
  3. A is false but R is true
  4. Both A and R are true but R is NOT the correct explanation of A

Answer

(2) Both A and R are true and R is the correct explanation of A

Solution

As per NCERT, the Bohr model is applicable to hydrogenic (one-electron) atoms only, such as H, He+, Li2+; it cannot be extended even to the two-electron helium atom.

In the Bohr model only the electrostatic attraction between the nucleus and one electron is considered.

In a many-electron atom the electrons also repel one another; this repulsion is not included in Bohr's formulation, so the model fails for such atoms.

A is true, R is true, and R explains why the model is limited to hydrogen-like atoms.

Answer: (2)

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Ques. 2JEE Main 2025, 3 April (Evening Shift)

An electron in the hydrogen atom initially in the fourth excited state makes a transition to nth energy state by emitting a photon of energy 2.86 eV. The integer value of n will be .

Ques. 3JEE Main 2025, 2 April (Morning Shift)

Considering Bohr's atomic model for hydrogen atom : Choose the correct answer from the options given below :

  1. (A), (B) only
  2. (A), (D) only
  3. (A), (C) only
  4. (B), (D) only
Ques. 4JEE Main 2025, 2 April (Evening Shift)

Assuming the validity of Bohr's atomic model for hydrogen-like ions the radius of Li++ ion in its ground state is given by 1Xa0, where X = (Where a0 is the first Bohr's radius.)

  1. 2
  2. 9
  3. 1
  4. 3
Ques. 5JEE Main 2025, 29 January (Evening Shift)

The number of spectral lines emitted by atomic hydrogen that is in the 4th energy level, is

  1. 3
  2. 6
  3. 1
  4. 0
Ques. 6JEE Main 2025, 28 January (Evening Shift)

The frequency of revolution of the electron in Bohr's orbit varies with n, the principal quantum number as:

  1. 1n4
  2. 1n2
  3. 1n3
  4. 1n
Ques. 7JEE Main 2025, 24 January (Morning Shift)

During the transition of electron from state A to state C of a Bohr atom, the wavelength of emitted radiation is 2000 and it becomes 6000 when the electron jumps from state B to state C. Then the wavelength of the radiation emitted during the transition of electrons from state A to state B is

  1. 4000
  2. 6000
  3. 2000
  4. 3000
Ques. 8JEE Main 2025, 22 January (Morning Shift)

An electron in the ground state of the hydrogen atom has the orbital radius of 5.3 10-11 m while that for the electron in third excited state is 8.48 10-10 m. The ratio of the de Broglie wavelengths of electron in the ground state to that in the excited state is

  1. 4
  2. 3
  3. 9
  4. 16

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