Structure of Atom NEET MCQ

Welcome to the Structure of Atom NEET MCQ (Multiple Choice Questions) guide. For NEET aspirants, having a deep understanding of atomic structure can set a solid foundation for the rest of chemistry. Each question is complemented by the correct answer and a concise explanation. Let’s put that knowledge to the test with these MCQs!

1. Who is credited with the discovery of the electron?

a) James Chadwick
b) Ernest Rutherford
c) J.J. Thomson
d) Neils Bohr

Answer:

c) J.J. Thomson

Explanation:

J.J. Thomson discovered the electron through his cathode ray experiments in 1897.

2. The atomic number of an element represents the number of:

a) Protons
b) Neutrons
c) Electrons
d) Nucleons

Answer:

a) Protons

Explanation:

The atomic number represents the number of protons in the nucleus of an atom.

3. Which model of the atom is known as the "plum pudding" model?

a) Bohr's model
b) Dalton's model
c) Rutherford's model
d) Thomson's model

Answer:

d) Thomson's model

Explanation:

J.J. Thomson proposed the "plum pudding" model, where electrons were embedded in a positively charged sphere.

4. Which particle is responsible for the atom's chemical properties?

a) Proton
b) Neutron
c) Electron
d) Photon

Answer:

c) Electron

Explanation:

Electrons participate in bond formation; hence, they determine the atom's chemical properties.

5. The nucleus of an atom was discovered by:

a) J.J. Thomson
b) Ernest Rutherford
c) James Chadwick
d) Max Planck

Answer:

b) Ernest Rutherford

Explanation:

Rutherford's gold foil experiment led to the discovery of the nucleus.

6. The dual nature of matter and radiation was proposed by:

a) Albert Einstein
b) Louis de Broglie
c) Max Planck
d) Werner Heisenberg

Answer:

b) Louis de Broglie

Explanation:

Louis de Broglie introduced the concept that particles can have wave-like characteristics.

7. The energy of an orbiting electron is:

a) Directly proportional to its distance from the nucleus
b) Inversely proportional to its distance from the nucleus
c) Not dependent on its distance from the nucleus
d) Equal to zero

Answer:

a) Directly proportional to its distance from the nucleus

Explanation:

According to Bohr's theory, the energy of an electron is directly proportional to its distance from the nucleus.

8. An alpha particle is equivalent to:

a) A helium nucleus
b) A hydrogen nucleus
c) An electron
d) A gamma ray

Answer:

a) A helium nucleus

Explanation:

An alpha particle consists of 2 protons and 2 neutrons, which is equivalent to a helium nucleus.

9. Which of the following quantum numbers gives the shape of an orbital?

a) Principal quantum number (n)
b) Magnetic quantum number (m)
c) Spin quantum number (s)
d) Azimuthal quantum number (l)

Answer:

d) Azimuthal quantum number (l)

Explanation:

The azimuthal quantum number (l) determines the shape of the orbital.

10. Who proposed the uncertainty principle?

a) Albert Einstein
b) Max Planck
c) Neils Bohr
d) Werner Heisenberg

Answer:

d) Werner Heisenberg

Explanation:

Heisenberg's uncertainty principle states that the position and momentum of a particle cannot be simultaneously measured with high precision.

11. Which of the following describes the number of subshells in the 4th shell of an atom?

a) 1
b) 2
c) 3
d) 4

Answer:

d) 4

Explanation:

The 4th shell (n = 4) has 4 subshells: s, p, d, and f.

12. Which subshell can accommodate a maximum of 10 electrons?

a) s
b) p
c) d
d) f

Answer:

c) d

Explanation:

The d-subshell has 5 orbitals, and each orbital can accommodate 2 electrons, so a total of 10 electrons.

13. An orbital can hold a maximum of ____ electrons.

a) 1
b) 2
c) 3
d) 4

Answer:

b) 2

Explanation:

An orbital can hold a maximum of 2 electrons with opposite spins.

14. Which quantum number gives information about the orientation of the orbital in space?

a) Principal quantum number (n)
b) Azimuthal quantum number (l)
c) Magnetic quantum number (m)
d) Spin quantum number (s)

Answer:

c) Magnetic quantum number (m)

Explanation:

The magnetic quantum number gives information about the orientation of an orbital within a subshell.

15. Which is the correct order of increasing energy for the following subshells?

a) 3d < 4s < 4p
b) 4s < 3d < 4p
c) 4s < 4p < 3d
d) 3d < 4p < 4s

Answer:

b) 4s < 3d < 4p

Explanation:

The energy of 4s is slightly less than that of 3d, and 4p has higher energy than both.

16. The spectral line of hydrogen atom which lies in the visible region is:

a) Lyman series
b) Balmer series
c) Paschen series
d) Brackett series

Answer:

b) Balmer series

Explanation:

The Balmer series of the hydrogen atom lies in the visible region of the electromagnetic spectrum.

17. Which of the following describes the electron distribution in oxygen atom?

a) 1s² 2s² 2p⁴
b) 1s² 2s² 2p³
c) 1s² 2s¹ 2p⁴
d) 1s² 2s² 2p⁵

Answer:

a) 1s² 2s² 2p⁴

Explanation:

Oxygen has 8 electrons. The distribution is 1s² 2s² 2p⁴.

18. The phenomenon which proves the wave nature of electrons is:

a) Photoelectric effect
b) Compton scattering
c) Electron diffraction
d) Pair production

Answer:

c) Electron diffraction

Explanation:

Electron diffraction, where electrons are diffracted by crystals, proves their wave nature.

19. Which of the following atomic models could not explain the stability of an atom?

a) Thomson's model
b) Bohr's model
c) Rutherford's model
d) Quantum mechanical model

Answer:

c) Rutherford's model

Explanation:

Rutherford's model couldn't explain why negatively charged electrons remain in orbit and don't fall into the positively charged nucleus.

20. The maximum number of electrons in the shell with principal quantum number n = 3 is:

a) 2
b) 8
c) 18
d) 32

Answer:

c) 18

Explanation:

The formula for the maximum number of electrons in a shell is 2n². For n = 3, it is 2(3²) = 18.

21. In the quantum mechanical model of an atom, which quantum number defines the overall size and energy of an orbital?

a) Principal quantum number (n)
b) Azimuthal quantum number (l)
c) Magnetic quantum number (m)
d) Spin quantum number (s)

Answer:

a) Principal quantum number (n)

Explanation:

The principal quantum number (n) defines the main energy level or shell in which the electron resides. It also gives an idea about the size of the orbital.

22. Who proposed the dual nature of matter?

a) Albert Einstein
b) Niels Bohr
c) Louis de Broglie
d) Werner Heisenberg

Answer:

c) Louis de Broglie

Explanation:

Louis de Broglie proposed the concept of wave-particle duality, suggesting that matter can exhibit both wave-like and particle-like properties.

23. The shape of an s-orbital is:

a) Linear
b) Planar
c) Spherical
d) Dumbbell

Answer:

c) Spherical

Explanation:

s-orbitals are spherically symmetrical about the nucleus.

24. In the hydrogen atom, which transition will produce an emission line with the highest frequency?

a) n = 3 to n = 2
b) n = 2 to n = 1
c) n = 4 to n = 1
d) n = 5 to n = 2

Answer:

c) n = 4 to n = 1

Explanation:

The energy difference and hence the frequency of emitted radiation is highest when the transition is from a higher energy level to the n=1 level.

25. Which of the following atomic models assumed electrons to revolve in specific non-radiating orbits?

a) Thomson's model
b) Bohr's model
c) Rutherford's model
d) Dalton's model

Answer:

b) Bohr's model

Explanation:

Bohr's model proposed that electrons move in specified stable orbits or shells around the nucleus without radiating energy.

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