Atomic Structure Multiple Choice Questions and Answers Pdf

This MCQ on Structure Of Atom Class 11 Questions And Answers Pdf is prepared by our LiveMCQs team for NEET. These questions are based on the chapter on Structure of Atom. Preparation of these questions has been taken from various books including NCERT, Previous year’s question papers, and model papers. So these Class 11 Chemistry Chapter 2 Important Questions With Answers cover all the topics of Structure of Atom. These MCQs are very helpful in your preparation for the National Eligibility cum Entrance Test-UG (NEET) and JEE Mains. We have provided these questions in PDF format which you can Download by clicking the link as “Atomic Structure Multiple Choice Questions And Answers Pdf” provide below.

Atomic Structure Multiple Choice Questions and Answers

1. The orientation of atomic orbitals depends on their

  • Spin quantum number
  • Magnetic quantum number
  • Azimuthal quantum number
  • Principal quantum number

Answer: magnetic quantum number

2. Who proposed the atomic theory?

  • John Dalton
  • Robert Millikan
  • J. J. Thomson
  • Neils Bohr

Answer: Robert Millikan

3. The isotopes of a neutral atom of an element differ in which of these?

  • Physical properties
  • Chemical properties
  • Atomic number
  • Mass number

Answer: Atomic number

4. The maximum mass of an atom is concentrated in which of these?

  • Nucleus
  • Neutrons
  • Protons
  • Electrons

Answer: Nucleus

5. An atom differs from an ion with respect to which of the following?

  • Number of protons
  • Nuclear charge
  • Number of electrons
  • Mass number

Answer: Number of electrons

6. The electronic configuration of atomic number 20 of an atom is which of the following?

  • 2, 6, 6, 2
  • 2, 8, 8, 2
  • 2, 4, 6, 2
  • 2, 4, 6, 2

Answer: 2, 8, 8, 2

7. Which of the following statements does not form a part of Bohrs model of hydrogen atom?

  • Energy of the electrons in the orbit is quantised
  • The electron in the orbit nearest the nucleus has the lowest energy
  • Electrons revolve in different orbits around the nucleus
  • The position and velocity of the electrons in the orbit cannot be determined simultaneously

Answer: The position and velocity of the electrons in the orbit cannot be determined simultaneously

8. What happens to the atomic number during a chemical reaction?

  • It increases
  • It changes
  • Remains the same
  • Changes alternatively

Answer: Remains the same

9. Atoms that have the same mass number and different atomic number are called?

  • Isotopes
  • Isotones
  • Isobars
  • Isomers

Answer: Isotopes

10. Which of the following determines the chemical properties?

  • Number of protons
  • Number of electrons
  • Number of neutrons
  • None of these

Answer: Number of electrons

11. Total number of orbitals associated with third shell will be __________.

  • 2
  • 4
  • 9
  • 3

Answer: 9

12. Which of the following properties of atom could be explained correctly by Thomson Model of atom?

  • Overall neutrality of atom
  • Spectra of hydrogen atom
  • Position of electrons, protons and neutrons in atom
  • Stability of atom

Answer: Overall neutrality of atom

13. Which of the following statements about the electron is incorrect?

  • It is a negatively charged particle
  • The mass of electron is equal to the mass of neutron
  • It is a basic constituent of all atoms
  • It is a constituent of cathode rays

Answer: The mass of electron is equal to the mass of neutron

14. Which of the following statement is not correct about the characteristics of cathode rays?

  • They start from the cathode and move towards the anode
  • They travel in straight line in the absence of an external electrical or magnetic field
  • Characteristics of cathode rays do not depend upon the material of electrodes in cathode ray tube
  • Characteristics of cathode rays depend upon the nature of gas present in the cathode ray tube

Answer: Characteristics of cathode rays depend upon the nature of gas present in the cathode ray tube.

15. Which of the following options does not represent ground state electronic configuration of an atom?

  • 1s2 2s2 2p6 3s2 3p6 3d8 4s2
  • 1s2 2s2 2p6 3s2 3p6 3d9 4s2
  • 1s2 2s2 2p6 3s2 3p6 3d10 4s1
  • 1s2 2s2 2p6 3s2 3p6 3d5 4s1

Answer: 1s2 2s2 2p6 3s2 3p6 3d9 4s2

16. Which of the following conclusions could not be derived from Rutherford’s α -particle scattering experiment?

  • Most of the space in the atom is empty
  • The radius of the atom is about 10–10 m while that of nucleus is 10–15 m
  • Electrons move in a circular path of fixed energy called orbits
  • Electrons and the nucleus are held together by electrostatic forces of attraction

Answer: Electrons move in a circular path of fixed energy called orbits

17. In which of the following pairs, the ions are iso-electronic?

  • Na+, Mg2+
  • Al3+, O–
  • Na+, O2-
  • N3–, Cl–

Answer: C, D

18. Maximum number of electrons in a subshell with l = 3 and n = 4 is

  • 10
  • 12
  • 14
  • 16

Answer: 14

19. The correct set of four quantum numbers for the valence electron of rubidium atom (Z = 37) is

  • 5, 0, 0, + 1/2
  • 5, 1, 0, + 1/2
  • 5, 1, 1, + 1/2
  • 6, 0, 0, + 1/2

Answer: 5, 0, 0, + 1/2

20. Identify the wrong statement in the following

  • The atomic radius of the elements increases as one moves down the first group of the periodic table
  • The atomic radius of the elements decreases as one moves across from left to right in the 2nd period of the
  • Amongst isoelectronic species, the smaller the positive charge on the cation, the smaller is the ionic radius
  • Amongst isoelectronic species, the greater the negative charge on the anion, larger is the ionic radius

Answer: Amongst isoelectronic species, smaller the positive charge on the cation, smaller is the ionic radius

21. A gas absorbs a photon of 355 nm and emits at two wavelengths. If one of the emissions is at 680 nm, the other is at

  • 518 nm
  • 1035 nm
  • 325 nm
  • 743 nm

Answer: 743 nm

22. The energy of an electron in first Bohr orbit of H-atom is –13.6 eV. The possible energy value of electron in the excited state of Li2+ is

  • – 122.4 eV
  • 30.6 eV
  • – 30.6 eV
  • 13.6 eV

Answer: – 30.6 eV

23. The electronic transitions from n = 2 to n = 1 will produce shortest wavelength in (where n = principal quantum state)

  • Li+2
  • He+
  • H
  • H+

Answer: Li+2

24. The energy required to break one mole of Cl – Cl bonds in Cl2 is 242 kJ mol–1. The longest wavelength of light capable of breaking a single Cl – Cl bond is (c = 3×108 ms–1 and NA = 6.02×1023 mol–1)

  • 594 nm
  • 640 nm
  • 700 nm
  • 494 nm

Answer: 494 nm

25. Mg2+ is isoelectronic with

  • Ca2+
  • Na+
  • Zn2+
  • Cu2+

Answer: Na+

26. Which one of the following sets of ions represents a collection of isoelectronic species?

  • K+, Cl–, Ca2+, Sc3+
  • Ba2+, Sr2+, K+, S2–
  • N3–, O2–, F–, S2–
  • Li+, Na+, Mg2+, Ca2+

Answer: K+, Cl–, Ca2+, Sc3+

27. Consider the ground state of Cr atom (Z = 24). The numbers of electrons with the azimuthal quantum numbers, l = 1 and 2 are, respectively:

  • 12 and 4
  • 12 and 5
  • 16 and 4
  • 16 and 5

Answer: 12 and 5

28. Electronic configuration of the outer shell of the element Gd with atomic number 64 is

  • 4f4 5d5 6s1
  • 4f3 5d5 6s2
  • 4f5 5d4 6s1
  • 4f7 5d1 6s2

Answer: 4f7 5d1 6s2

29. Maximum number of electrons in a subshell can be

  • 4l + 2
  • 4l – 2
  • 2n2
  • 2l + 1

Answer: 4l + 2

30. A gas X has Cp and Cv ratio as 1.4, at NTP 11.2 L of gas X will contain_______ number of atoms

  • 1.2 × 1023
  • 3.01 × 1023
  • 2.01 × 1023
  • 6.02 × 1023

Answer: 6.02 × 1023

31. Number of unpaired electrons in N2+

  • 3
  • 1
  • 2
  • 0

Answer: 1

32. The excitation energy of a hydrogen atom from its ground state to its third excited state is

  • 12.75 eV
  • 0.85 eV
  • 10.2 eV
  • 12.1 eV

Answer: 12.75 eV

33. 3p orbital has _____ radial nodes

  • three
  • two
  • one
  • none

Answer: one

34. A 0.66 kg ball is moving with a speed of 100 m/s. Find its wavelength

  • 6.6 × 10-34 m
  • 6.6 × 10-32 m
  • 1.0 × 10-32 m
  • 1.0 × 10-35 m

Answer: 1.0 × 10-35 m

35. If an atom has four unpaired electrons, what is likely to be the total spin of the electron?

  • 1
  • 2.5
  • 2
  • 4

Answer: 2

36. The electronic configuration for oxygen is written as 1s2 2s2 2p4. Which rule will this configuration be violating?

  • Aufbau’s principle
  • Hund’s rule
  • Pauli’s exclusion principle
  • None of the above

Answer: None of the above

37. What is the sequence to label the subshells in an atom?

  • S, p, d, f, g
  • S, p, p, f, d
  • S, s, p, p, d, f, g
  • S, p, g, d, f

Answer: S, p, d, f, g

38. If both the K and L shells are full, what would be the atomic number of that element?

  • 20
  • 14
  • 10
  • 16

Answer: 10

39. Nickel has atomic number 28. Choose the correct electronic configuration for Nickel.

  • 1s2 2s2 2p4 3s2 3p8 3d10
  • 1s2 2s2 2p6 3s2 3p6 3d8 4s2
  • 1s2 2s2 2p4 3s2 3p6 4s2
  • 1s2 2s2 3s2 3p8 3d10

Answer: 1s2 2s2 2p6 3s2 3p6 3d8 4s2

40. Which of the following determines the atomic number of an atom?

  • Number of electrons
  • Number of protons
  • Number of electrons and protons
  • Number of protons and neutrons

Answer: Number of protons

41. Which of the following is responsible for the mass of an atom?

  • Only protons
  • Only neutrons
  • Neutrons and protons
  • Protons and electrons

Answer: Neutrons and protons

42. An atom has mass number 37 and atomic number 17. Find the number of protons

  • 21
  • 22
  • 17
  • 20

Answer: 17

43. What is the formula for a mass number of an atom?

  • Number of protons + number of electrons
  • Number of neutrons + number of electrons
  • Number of protons + number of neutrons
  • None of these

Answer: Number of protons + number of neutrons

44. Who discovered electron?

  • Rutherford
  • J. J. Thomson
  • Neils Bohr
  • James Chadwick

Answer: J. J. Thomson

45. Which of the following statements about the electron is incorrect?

  • It is a constituent of cathode rays
  • The mass of an electron is equal to the mass of a neutron
  • It is a basic constituent of all atoms
  • It is a negatively charged particle

Answer: The mass of an electron is equal to the mass of a neutron

46. How many angular nodes for 4d orbital?

  • 4
  • 3
  • 2
  • 1

Answer: 2

47. Total number of orbitals associated with the third shell will be __________.

  • 2
  • 4
  • 9
  • 3

Answer: 9

48. Two atoms are said to be isobars if

  • They have the same atomic number but the different mass number
  • They have the same number of electrons but different numbers of neutrons
  • They have the same number of neutrons but different numbers of electrons
  • The Sum of the number of protons and neutrons is the same but the number of

Answer: sum of the number of protons and neutrons is the same but the number of

49. Which of the following properties of atom could be explained correctly by Thomson Model of atom?

  • Overall neutrality of atom
  • Spectra of hydrogen atom
  • Position of electrons, protons and neutrons in atom
  • Stability of atom

Answer: Overall neutrality of atom

50. Orbital angular momentum depends on __________.

  • l
  • n and l
  • n and m
  • m and s

Answer: l

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