Ecat Entry Test Chemistry Atomic Structure MCQs

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Atomic Structure, Atomic Structure, protons, nucleus, Atomic Models MCQS Online Preparation Sample Paper Questions with Answer

Students must fundamentally understand chemistry atomic structure to grasp the concept of atomical elements along with particles and their systems of operation. Matter derives its building components from atoms while having proton neutron and electron particles inside. Elemental physical properties and both chemical bonding and reactions derive their nature from the way these particles organize themselves. Students who intend to succeed in ECAT Entry Test MCQs need full competency in atomic structure knowledge to excel in chemistry questions. The guide serves as a detailed reference which includes essential guidance along with exam questions to enhance preparation.

Ecat Entry Test Chemistry Atomic Structure MCQs

Fundamental Concepts of Chemistry Atomic Structure

1. Subatomic Particles

Atoms consist of three primary subatomic particles:

  • Protons: Positively charged particles found in the nucleus.
  • Neutrons: Neutral particles, also present in the nucleus, contribute to atomic mass.
  • Electrons: Negatively charged particles orbiting the nucleus in distinct energy levels.

2. Atomic Models and Theories

Several atomic models have been developed to explain atomic behavior:

  • Dalton’s Atomic Theory: Proposed atoms as indivisible particles.
  • Thomson’s Model: Described the atom as a “plum pudding” model with electrons embedded in a positively charged sphere.
  • Rutherford’s Model: Introduced the nuclear structure of the atom.
  • Bohr’s Model: Proposed electron shells and quantized energy levels.
  • Quantum Mechanical Model: Provides a probabilistic understanding of electron positions.

3. Quantum Numbers and Electron Configuration

Quantum numbers describe the arrangement of electrons:

  • Principal Quantum Number (n): Represents the main energy level.
  • Azimuthal Quantum Number (l): Defines the shape of the orbital.
  • Magnetic Quantum Number (m): Determines the orbital’s orientation.
  • Spin Quantum Number (s): Represents electron spin direction.

4. Ionization Energy and Electron Affinity

  • Ionization Energy: The energy required to remove an electron from an atom.
  • Electron Affinity: The energy released when an atom gains an electron.

Sample MCQs on Chemistry Atomic Structure

1. Bohr model of atom does not explain

  • All of these
    correct
  • Zeeman effect
  • Origin of line in H₂ spectrum
  • Stark effect

2. Each electron in an atom must have its own unique set of quantum numbers. This is a statement of:

  • Aufbau principle
  • Pauli exclusion principle
    correct
  • Periodic law
  • Hund’s rule

3. A proton is quite identical to

  • Ionized hydrogen
    correct
  • Ionized hydrogen molecule
  • hydroponic ion
  • α – Particle

4. Which are not electromagnetic radiations?

  • Sound waves
    correct
  • X – rays
  • Radio waves
  • Proton

5. The nature of positive rays depends upon

  • All of the above
  • The nature of electrode
  • The nature of residual gas
    correct
  • The nature of discharge tube

6. Ionization energies of the elements of group VA are greater than those of Group. VI A. The reason is that.

  • Group V A elements have greater shielding effect
  • Group VI A elements have greater shielding effect
  • Group V A element have less electronegativity
  • Group V A element half-filled atomic orbitals
    correct

7. in the ground state of an atom, the electron is present

  • Nearest to the nucleus
    correct
  • In the nucleus
  • In the second shell
  • Farthest form the nucleus

8. Which orbital of the following has a principal quantum number of 3 and an angular momentum quantum number of 27?

  • 3f
  • 3s
  • 3dcorrect
  • 4f

9. The velocity of photon is:

  • Depends on its source
  • Independent of its wavelengthcorrect
  • Depends on its wavelength
  • Equal to square

10. The wave number of the light emitted by a certain source is 2 x 10⁶m . The wavelength of this light is:

  • 200nm
  • 500m
  • 500nmcorrect
  • 5 x 10⁷ m

11. The principle quantum number describes the

  • Orientation from the orbital
  • Shape of the orbital
  • Distance from the nucleus
    correct
  • Spin of the electron

12. Which of the following is not sub-atomic particle?

  • Deuteron
    correct
  • Neutron
  • Electron
  • Proton

13. How many orbitals are allowed for principle quantum number (n) of 3?

  • 9correct
  • 5
  • 8
  • 6

14. When cathode rays strike the anode metal, X-rays are emitted and not the positive rays. The reason is that cathode rays are

  • Heated
  • Knocked out electrons from anode that emit X-rays when outer electrons take their place
  • Absorbed by the nucleuscorrect
  • Material particles

15. Which of the following is not charged particle?

  • Hydrogen
  • Electron
  • Proton
  • Neutron
    correct

16. Point out the orbitals which are degenerate in a multi electron atom

  • 3d orbitalscorrect
  • 3s, 3p, 3d orbitals
  • 2d orbitals
  • 1s, 2s orbitals

17. The mass of a neutron is times greater than the mass of electron

  • 1840correct
  • 1480
  • 2000
  • 540

18. Elements with _______ first ionization energies and _____ electron affinities generally form cations. Choose the correct point

  • High, very negative
  • Low very negative
  • Low, positive or slightly negative
    correct
  • High, positive or slightly negative

19. When 6d orbital is complete, the entering electron goes into

  • 7s
  • 7f
  • 7p
    correct
  • 7d

20. Millikan determined the charge on electron in oil drop experiment. It value is:

  • 1.602 x 10¯²³ C
  • 6.625 x 10¯³⁴ C
  • 1.602 x 10²³ C
  • 1.602 x 10¯¹⁹ C
    correct

21. The mass of neutron is in the range of

  • 1.6750 x 10¯²³ kg
  • 1.6750 x 10¯²⁶ kg
  • 1.6750 x 10¯²⁷kgcorrect
  • 1.6750 x 10¯²² kg

22. Bohr’s model of atom is contradicted by:

  • Quarternization of energy of electrons
  • Heiesenberg’s uncertainity principle
    correct
  • Planck’s quantum theory
  • Quarternization of angular members

23. An oxygen atom has mass of

  • 2.657 x 10¯²³g
    correct
  • 5.316 x 10¯²³g
  • 5.316 x 10²³g
  • 16g

24. The atomic radii of elements lie in the order of

  • 10¹² cm
  • 10¯¹² cm
  • 10⁸ cm
  • 10¯⁸ cm
    correct

25. Chlorine atom has set of n, l, m quantum number for the unpaired electrons:

  • 3,1,1
    correct
  • 3,0,0
  • 2,1,1
  • 2,1,0

Conclusion

The mastery of Chemistry Atomic Structure leads to better success in the ECAT Entry Test. Learning about atomic models along with subatomic particles’ fundamental properties and quantum numbers produces advanced problem-solving abilities in chemistry. MCQ practice enhances both conceptual understanding and improves student performance in tests.  Defining the essential subjects while using these practice questions will strengthen your preparation.

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