Army Medical College (AMC) Entry Test Chemistry: Atomic Structure MCQs

Practice Atomic Structure MCQs for Army Medical College (AMC) Entry Test Chemistry — topic-wise sets with solved answers.

Army Medical College (AMC) Entry Test Chemistry: Atomic Structure MCQs — sample questions

  1. Question 1

    Q1. During a discharge tube experiment, high-velocity cathode rays strike the glass walls of the tube. What is the observable result of this specific interaction?

    • A) Produce X-rays immediately
    • B) Produce a greenish fluorescence
    • C) Cause the glass to melt
    • D) Reflect back to the cathode

    Answer: Produce a greenish fluorescence

    Explanation: Cathode rays produce fluorescence when striking glass; X-rays are only produced when these rays hit heavy metal targets like tungsten.

  2. Question 2

    Q2. In the ionization chamber of a mass spectrometer, what mechanism is utilized to convert vaporized atoms into positive ions before acceleration?

    • A) Thermal excitation of atoms
    • B) Proton bombardment
    • C) Electron bombardment
    • D) Magnetic field induction

    Answer: Electron bombardment

    Explanation: High-energy electrons knock out valence electrons from vaporized atoms to form positive ions; thermal ionization is used for different applications.

  3. Question 3

    Q3. A researcher attempts to determine the exact trajectory of an electron within an atom. Which pair of variables is fundamentally impossible to measure simultaneously?

    • A) Position and momentum
    • B) Mass and velocity
    • C) Charge and energy
    • D) Spin and direction

    Answer: Position and momentum

    Explanation: Heisenberg's principle states position and momentum cannot be measured simultaneously; Bohr's model fails because it assumes fixed paths for electrons.

  4. Question 4

    Q4. In the production of characteristic X-rays, a K-alpha photon is emitted when an electron transition occurs between which two specific energy levels?

    • A) M-shell to K-shell
    • B) L-shell to M-shell
    • C) K-shell to L-shell
    • D) L-shell to K-shell

    Answer: L-shell to K-shell

    Explanation: K-alpha X-rays occur when an L-shell electron fills a K-shell vacancy; K-beta transitions involve M-shell electrons falling to the K-shell.

  5. Question 5

    Q5. A student needs to calculate the total number of orbitals available in the M-shell (n=3). Which formula correctly determines this value?

    • A) 2n
    • B) 2n + 1
    • C) n^2
    • D) 2n^2

    Answer: n^2

    Explanation: The formula n-squared gives the total orbitals in a shell; 2n-squared calculates the maximum number of electrons instead.

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