JEE Main · 2023 · Shift-ImediumATOM-133

Statement I: According to Bohr's model of hydrogen atom, the angular momentum of an electron in a given stationary…

Structure of Atom · Class 11 · JEE Main Previous Year Question

Question

Statement I: According to Bohr's model of hydrogen atom, the angular momentum of an electron in a given stationary state is quantised. Statement II: The concept of electron in Bohr's orbit violates the Heisenberg's uncertainty principle.

Choose the most appropriate answer from the options given below:

Options
  1. a

    Statement I is incorrect but Statement II is correct

  2. b

    Both Statement I and Statement II are correct

  3. c

    Both Statement I and Statement II are incorrect

  4. d

    Statement I is correct but Statement II is incorrect

Correct Answerb

Both Statement I and Statement II are correct

Detailed Solution

🧠 The Model Collision Bohr's model was a brilliant bridge, but it fundamentally clashes with the modern Heisenberg Uncertainty Principle.

🗺️ The Logic Check

  • Statement I: TRUE. Bohr's second postulate explicitly states that angular momentum is restricted to integral multiples of h/2πh/2\pi (mvr=nh/2πmvr = nh/2\pi).
  • Statement II: TRUE. Bohr's model describes electrons as moving in fixed circular paths with precise velocities. However, Heisenberg proved you cannot know both the exact path (position) and the exact speed (momentum) at the same time. Bohr's "fixed tracks" are physically impossible.

The Theory Evolution Bohr assumed the electron was a predictable planet. Heisenberg proved it was a random cloud. This single conflict is why Bohr's model was eventually discarded for the Wave Mechanical model (Schrödinger).

⚠️ Common Traps Don't think that because Bohr is taught, he must be "correct." His model is useful for math, but logically flawed at high resolution!

Answer: (b)\boxed{\text{Answer: (b)}}

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